Python Practice Problems

Python (945)

• Activity Time Ledger - easy - Matching activities. One runtime.
• A per-request timeout of 2.0 seconds cancels any fetch that takes longer - medium
• Append "python" to the "languages" list inside the dev dictionary - medium
• Apply De Morgan's Laws - medium
• A Semaphore caps how many fetches run at once - medium
• Assign display_name using 'or' for default value - medium
• A user requests certain columns from a database - medium
• A variable called city is provided - medium
• A variable called filename holds "photo.png" - medium
• A variable called phone holds "(555) 867-5309" - medium
• A variable called text holds "Hello World" - medium
• A variable called text holds "programming" - medium
• A variable called word holds the string "developer" - medium
• Batch Partitioner - medium - One pile becomes many. Split wisely.
• Batch Records - medium - Too many at once. Break them into groups.
• Batch With Metadata - easy - The list gets chopped.
• Build a data query pipeline: filter to only in-stock products, sort by price descending, and take th - medium
• Build a decision table mapping (is_member, total >= 100) tuples to discount percentages - medium
• Build a lookup dictionary from a list of user dicts, indexed by email, using a dict comprehension - medium
• Build a prefix sum array from [3, 1, 4, 1, 5] - medium
• Build a value-to-index map from the list ['apple', 'banana', 'cherry', 'date'] using a dict comprehe - medium
• Caesar Shift Check - easy - The key turns. Does it open?
• Calculate the total by adding bill_amount and tip_amount. - medium
• Calculate total discrepancies: the count of IDs that appear in only one database. - medium
• Calculate total elements in the matrix by summing the length of each row. - medium
• Calculate total_saved by summing the difference between original and discounted prices. - medium
• Call analyze_text with 'Python is a great language' and unpack the three return values into variable - medium
• Call the handler function retrieved from the dispatch dictionary. - medium
• Categorize the variable `age` into life stages using if-elif-else: print "child" if age < 13, "teen" - medium
• Character Occurrence Map - easy - Character frequency as a map.
• Char Profile - medium - Every character in the string tells a story.
• Check if the number 999 exists in both a list and a set containing range(1000) - medium
• Check if the variable `color` equals "blue" - medium
• Check whether a user has all required permissions using the subset operator (<=) - medium
• Check whether 'example' appears in the url using the 'in' operator. - medium
• Check whether the error is within the tolerance and store the boolean result in is_ok. - medium
• Coalesce Fields - easy - Nulls are hiding. Fill them in.
• Column Max - easy - One value rules the column.
• Column Range - easy - From minimum to maximum. What is the spread?
• Column Sum - easy - Add up the column. Every value counts.
• Common Prefix - hard - They all start the same way. How far?
• Compare list and tuple memory sizes and store whether the tuple is more compact as a boolean. - medium
• Compare user lists from two months - medium
• Complete both type-hinted functions: add_numbers returns the sum, make_greeting returns 'Hello, <nam - medium
• Complete calculate_bmi to return the BMI formula: weight divided by height squared, rounded to 1 dec - medium
• Complete classify_number: add a guarded case for even numbers (n % 2 == 0) and a default case return - medium
• Complete classify_temp using early returns: 'freezing' below 0, 'cold' below 20, 'warm' below 30, 'h - medium
• Complete describe_status using match-case: 200 returns 'OK', 404 returns 'Not Found', 500 returns 'S - medium
• Complete double_value: double x locally and print 'Inside: ' followed by the value - medium
• Complete fahrenheit_to_celsius to return the conversion formula: (fahrenheit - 32) * 5 / 9. - medium
• Complete flatten: if an item is a list, recurse and extend the result; otherwise append the item dir - medium
• Complete get_discount by storing the computed rate in the cache before returning it. - medium
• Complete get_first: return 'N/A' if items is None or empty, otherwise return the first element. - medium
• Complete has_even: return True immediately when an even number is found (early return pattern). - medium
• Complete is_sorted: compare consecutive pairs, returning False if any element is greater than the ne - medium
• Complete log_event: when show_level is True, print the message prefixed with the level in brackets. - medium
• Complete normalize_keys: return a new dict with all keys run through _normalize, values unchanged. - medium
• Complete power_cached: on a cache miss, store the computed result - medium
• Complete process_contacts: loop through contacts, keep only those with valid emails, clean the names - medium
• Complete safe_average: after the guard clauses, return the average (sum divided by length). - medium
• Complete safe_get: return the element at the given index inside the try block. - medium
• Complete send_message to conditionally append ' [URGENT]' when urgent is True, and ' | CC: <cc>' whe - medium
• Complete Tag's __enter__ (print opening tag, return self) and __exit__ (print closing tag). - medium
• Complete the grade function: return 'C' for scores from 70 to 79 using a chained comparison. - medium
• Complete the inner add function: add the amount to total and return the new total. - medium
• Complete the inner function to return the greeting and name combined with a comma and exclamation ma - medium
• Complete the inner greet function to return the greeting, name, and punctuation combined. - medium
• Complete the Logger's __exit__ method to print 'Finished' when the with block ends. - medium
• Complete the loop: update smallest whenever you find a number smaller than the current minimum. - medium
• Complete the multiply function to return the product of its two parameters. - medium
• Complete the nested functions: average() returns total divided by number of days (rounded to 1 decim - medium
• Complete the nested functions: is_passing returns True if grade >= threshold - medium
• Complete the O(n) two-sum: check if the complement (target - num) is in the seen set, then add the c - medium
• Complete the recursive case: when an item is a list, add the result of recursing into it to the tota - medium
• Complete the state machine loop: look up the next state from the transitions dict using the current - medium
• Complete the validation by printing f-strings that check code3.isdigit() and code1.isalpha(). - medium
• Complete validate: check if 'name' and 'email' are in the record - medium
• Complete validate_score: after all guard clauses pass, return 'valid: ' followed by the score. - medium
• Compute 2 raised to the power of 8 using the ** operator and store the result in a variable called r - medium
• Convert the page_views list into a set called unique_pages - medium
• Convert the string word to a set of unique characters - medium
• Count the frequency of each word in the list using a for loop and .get(word, 0) + 1 - medium
• Create a copy of base using .copy(), then use .update() to merge overrides into the copy - medium
• Create a `db_config` dictionary with "host" set to "db.example.com", "port" set to 5432, and "name" - medium
• Create a deque from [1, 2, 3] - medium
• Create a deque with maxlen=4 - medium
• Create a deque with maxlen=4 - medium
• Create a dictionary called `medals` where the integer key 1 maps to "Gold", 2 maps to "Silver", and - medium
• Create a dictionary called `pet` with the key "name" set to "Luna" and the key "species" set to "cat - medium
• Create a dictionary called `product` with "name" set to "Laptop", "price" set to 999, and "in_stock" - medium
• Create a dictionary called server with keys 'host', 'port', and 'status' mapped to 'web-01.prod', 80 - medium
• Create a dictionary user with keys 'name' set to 'Ada' and 'age' set to 36 - medium
• Create a frozenset from the list [3, 1, 2, 3, 1] - medium
• Create a global variable total set to 0 - medium
• Create a lambda function called double that takes one argument and returns it multiplied by 2 - medium
• Create a list called foods containing "pasta", "sushi", and "tacos" - medium
• Create a list called profile containing the string "Ada", the integer 30, and the boolean True - medium
• Create a list original = [10, 20, 30] - medium
• Create a list, tuple, dict, and set - medium
• Create a maxlen=5 deque and append 8 events - medium
• Create an empty dictionary called `profile` - medium
• Create an empty dictionary called `scores` - medium
• Create an empty set using the correct syntax (remember, {} makes a dictionary) - medium
• Create a nested list original = [[1, 2], [3, 4]] - medium
• Create a Pipeline dataclass with name, steps (default empty list via field), and retries (default 3) - medium
• Create a set containing the values 5, 10, 15, 5, 10 - medium
• Create a shallow copy of data using .copy() - medium
• Create a single-element tuple called solo containing only the value 42 - medium
• Create a tuple called coords containing the values 10, 20, and 30 - medium
• Create a tuple called db_config storing the host 'db.example.com', port 5432, and database name 'ana - medium
• Create a variable age set to 25 - medium
• Create a variable called age set to 25 and a variable called name set to "Maya" - medium
• Create a variable called city and set it to "Denver" - medium
• Create a variable called city and set it to "Portland" - medium
• Create a variable called lines and set it to the string "Line 1\nLine 2" (using the \n escape sequen - medium
• Create a variable called name and assign it the string "Python" - medium
• Create a variable called year and assign it the integer 2024 - medium
• Create a variable count set to 10 - medium
• Create a variable price set to 40 and a variable tax_rate set to 0.07 - medium
• Create the URL slug by joining slug_words with '-', lowercasing each word. - medium
• Create three variables: count = 7, price = 4.99, and label = "sale" - medium
• Create two Counters: c1 = Counter({'a': 3, 'b': 1}) and c2 = Counter({'a': 1, 'b': 4}) - medium
• Create two Counters: c1 = Counter({'x': 3, 'y': 1}) and c2 = Counter({'x': 1, 'y': 2}) - medium
• Cumulative Sum - medium - The total grows with every row.
• Data Quality Report - hard - The data is not as clean as it looks.
• Deep Flatten - medium - Nested deep. Flatten everything.
• Deep Get - medium - Nested deep. Reach in and grab it.
• Define add_item(item, items=None) that creates a new list if items is None, appends item, and return - medium
• Define a decorator shout(fn) that returns a wrapper which uppercases the return value of fn - medium
• Define a function add(a, b) that returns a + b - medium
• Define a function apply_discount(price, percent) that returns price minus (price * percent / 100) - medium
• Define a function called describe_pet that takes two parameters: name and animal - medium
• Define a function called divide_safe that takes two parameters a and b - medium
• Define a function called full_name that takes two parameters, first_name and last_name, and returns - medium
• Define a function called is_even that takes a number and returns True if it is even, False otherwise - medium
• Define a function called make_greeting that takes a name parameter, creates a local variable greetin - medium
• Define a function called power that takes a base and an optional exponent parameter (default 2) - medium
• Define a function called print_banner that prints '**********' (ten asterisks) - medium
• Define a function called print_divider that prints a line of 15 equals signs - medium
• Define a function called say_hello that prints 'Hello, functions!' on one line - medium
• Define a function called say_hello that prints two lines: "Hello, World!" and "Functions are great!" - medium
• Define a function called square that takes one parameter and returns its square (the number multipli - medium
• Define a function classify_score(score) that returns 'A' if score >= 90, 'B' if score >= 80, 'C' if - medium
• Define a function count_multiples(limit, step) that uses a for loop over range(1, limit + 1) and ret - medium
• Define a function describe(**fields) that prints each 'key=value' line in insertion order - medium
• Define a function double(n) that returns n * 2 - medium
• Define a function first_over(threshold, values) that returns the first value in values greater than - medium
• Define a function first_positive(nums: list) -> int that returns the first element that is greater t - medium
• Define a function format_item(name, qty) that prints the quantity followed by 'x' and the name, like - medium
• Define a function greet(name, greeting="Hello") that returns greeting + ", " + name + "!" - medium
• Define a function greet(name) that prints 'Hello, ' followed by name and '!' - medium
• Define a function label(name: str, tier: str = 'standard') -> str that returns a string like 'Ada [s - medium
• Define a function make_counter() with a docstring 'Counter closure; each call bumps the count by 1.' - medium
• Define a function make_multiplier(factor) that returns an inner function multiply(n) that returns n - medium
• Define a function make_tag(name, count) with a docstring 'Return a label like 3x Widget.' that retur - medium
• Define a function parse_name(full) that splits full on a single space and returns (first, last) - medium
• Define a function running_total(n) using a while loop that starts count at 1 and total at 0 - medium
• Define a function stats(nums) that returns a tuple of (minimum, maximum, average) - medium
• Define a function tax(price: float, rate: float = 0.05) -> float that returns price * rate - medium
• Define a function total(*nums) that returns the sum of all arguments - medium
• Define a function triple(n) with the docstring 'Triple the input value.' that returns n * 3 - medium
• Define a generator countdown(n) that yields n, n-1, ..., 1 using yield - medium
• Define area(w, h) returning w * h - medium
• Define a recursive function factorial(n) with a base case at n <= 1 returning 1, else return n * fac - medium
• Define categorize(score) that returns 'pass' if score >= 60, otherwise 'fail' - medium
• Define compose(f, g) that returns a function applying f(g(x)) - medium
• Define connect(host="localhost", port=5432, ssl=True) that returns host + ":" + str(port) + ":ssl=" - medium
• Define create_user(name, email, role="viewer") that returns a dict with those three keys - medium
• Define get_greeting(name) that returns 'Hello, ' + name (do NOT use print inside the function) - medium
• Define get_stats(numbers) that returns three values: the sum, the length, and the average (sum/lengt - medium
• Define get_user() that returns "Alice", 30, "Seattle", "Engineer" - medium
• Define log_message(level, *messages) that prints each message prefixed with "[LEVEL] " - medium
• Define memoize(fn) that returns a wrapper using a dict cache keyed by the args tuple - medium
• Define show_config(**kwargs) that prints each key-value pair as "key: value" (iterate kwargs.items() - medium
• Define square(n) returning n * n and add_one(n) returning n + 1 - medium
• Define sum_all(*numbers) that returns the sum of all arguments - medium
• Demonstrate O(1) dict lookup vs O(n) list search - medium
• Demonstrate O(1) set membership vs O(n) list search - medium
• Demonstrate the difference between sort() and sorted() - medium
• Detect Cycle in Sequence - medium - Follow the chain long enough and it might loop back.
• Detect Outliers - medium - Most values are normal. Some are suspicious.
• Diagonal Extract - medium - Not every value sits in a row or column.
• Dice Roll Scoring - medium - The pattern rewards the patient.
• Dictionary Key Intersection - medium - Two dictionaries. What do they share?
• Distribute Values Into Container Types - medium - Round-robin the values. Keep rotating.
• Dominant Element - easy - Majority element. Appears more than half the time.
• Encode text to UTF-8 bytes, then decode it back to a string. - medium
• Encode the greeting to UTF-8 bytes - medium
• Even Filter - easy - Only the even ones survive.
• Execution Timer Wrapper - medium - Function wrapped with a timer. Duration captured on exit.
• Explode List - easy - One row holds many values. Unpack it.
• Extract and sum all the digits of the number stored in num - medium
• Extract Domain - easy - The domain is buried in the string.
• Extract Leaf Values - medium - The tree has leaves. Pluck them.
• Find all values that appear more than once in the list - medium
• Find both the minimum and maximum of the list in a single pass using O(1) extra space - medium
• Find Indices - medium - It is in there somewhere. Where exactly?
• Find Mode - medium - One value appears more than the rest.
• Find returning users (the intersection of today and yesterday) using the & operator. - medium
• Find the common elements between two lists using sets for efficient O(n) membership testing - medium
• Find the skills that appear in BOTH the frontend and backend sets using the & operator - medium
• Find the smallest gap between any two numbers in [8, 1, 14, 3, 21] - medium
• First use filter() to keep only users where "active" is True, then use map() to extract their names - medium
• Flatten the 2D list [[1, 2], [3, 4], [5, 6]] into a single flat list using a nested list comprehensi - medium
• Flatten the Feed - easy - Nested lists, all the way down.
• Flatten the Nest - easy - Mixed nesting. One flat list out.
• For each number in the list, print it zero-padded to 5 digits using an f-string with :05d format - medium
• Format: price with commas and 2 decimals, ratio as a percentage with 1 decimal, label right-aligned - medium
• Full Outer Zip - medium - Two sides. No value left behind.
• gather returns results in the ORDER you submitted the tasks, not the order they finish - medium
• Given a = {1, 2, 3, 4} and b = {3, 4, 5, 6}, print the sorted list of elements that are in a or b bu - medium
• Given a = [1, 2, 3, 4] and b = [3, 4, 5, 6], print the sorted list of elements that are in both a an - medium
• Given a = [1, 2, 3] and b = [4, 5, 6], create combined = a + b - medium
• Given a = 1 and b = 2, swap them using tuple unpacking in a single line - medium
• Given a = 3 and b = 4, compute the hypotenuse using a ** 2 + b ** 2 (do not take the square root) - medium
• Given a dictionary of cities and their populations, use a for loop over .values() to calculate the t - medium
• Given age = 16 and has_license = True, print 'can drive' if age >= 16 and has_license is True, other - medium
• Given age = 25 and has_passport = True, using a single compound expression with De Morgan simplifica - medium
• Given age and has_id, use the 'and' operator to check if the user can enter (age >= 21 AND has_id is - medium
• Given a = 'listen' and b = 'silent', determine if they are anagrams by comparing sorted character se - medium
• Given a list of login events events = ['ada', 'linus', 'ada', 'grace', 'linus', 'ada'], build a dict - medium
• Given a list of numbers nums = [7, 2, 5, 3, 8, 1, 4] and k = 3, find the k largest values using heap - medium
• Given a list of product dicts, use a list comprehension to extract the names of all products with a - medium
• Given amount = 1234567.891, print it formatted as a string with a comma thousands separator and exac - medium
• Given apples and oranges, add them together and store the result in a variable called total_fruit - medium
• Given a state machine where transitions is {'idle': 'running', 'running': 'done', 'done': 'done'}, s - medium
• Given a `status` string and two safe values `safe1` and `safe2`, print "alert" if the status does no - medium
• Given a string, build its reverse by starting with an empty string and looping through each characte - medium
• Given a = ["x", "y"] and b = ["z"], create a new list called combined using the + operator to join a - medium
• Given base = [1, 2, 3] and extra = [4, 5, 6], use extend() to add all items from extra into base - medium
• Given blocked_ids = {42, 17, 99, 23} and requests = [12, 17, 5, 99, 42, 7, 23, 100], count how many - medium
• Given colors and sizes, use nested for loops to print every combination in the format 'color-size', - medium
• Given colors = ["red", "green", "blue", "yellow"], create a reversed copy using slice notation [::-1 - medium
• Given colors = ["red", "green", "blue", "yellow", "purple"], print the last item using negative inde - medium
• Given count_str = '7' and word = 'apple', convert count_str to an integer and multiply word by that - medium
• Given defaults = {'theme': 'light', 'font': 12, 'wrap': True} and overrides = {'theme': 'dark', 'tab - medium
• Given events = ['login', 'view', 'login', 'purchase', 'view', 'login', 'view'], use Counter to get c - medium
• Given expr = '(()())', use a list as a stack to determine if the parentheses are balanced - medium
• Given first = 'Ada' and last = 'Lovelace', build full_name by concatenating them with a single space - medium
• Given first_name and last_name, create a variable called full_name by concatenating them with a spac - medium
• Given fruits, use enumerate() to print each fruit with its index in the format 'index: fruit' - medium
• Given grades = ["A", "B", "A", "C", "A", "B", "A"], use .count() to print how many times "A" appears - medium
• Given greeting = 'HELLO' and name = 'world', print greeting.lower() followed by a comma, a space, an - medium
• Given grid = [[0] * 3 for _ in range(3)], set grid[1][1] = 9 and print grid - medium
• Given grid (a list of lists of integers), use nested loops to calculate the sum of all values - medium
• Given groceries = ["milk", "eggs", "bread", "eggs", "cheese"], remove "eggs" from the list and print - medium
• Given ids = [101, 102, 103, 104, 105], write an O(1) lookup that prints ids[0] and ids[len(ids) - 1] - medium
• Given is_active, print its type - medium
• Given is_blocked, use the 'not' operator to determine if the user can_post (the opposite of is_block - medium
• Given is_subscriber, is_banned, and is_admin, a user can access a premium feature if they are a subs - medium
• Given items = [3, 8, 2, 7, 5], write a simple O(n) loop that finds the maximum value without using m - medium
• Given items = ['a', 'b', 'c', 'd', 'e'], implement an O(n) single-pass that builds a reverse list wi - medium
• Given items, initialize last to None before the loop - medium
• Given items = ["pen", "book", "pen", "eraser", "pen"], use .index() to print the index of "book" - medium
• Given items = [], print the first item if the list is non-empty, otherwise print 'empty' - medium
• Given keys and values, use dict() and zip() to create a dictionary called info - medium
• Given labels = ['a', 'b', 'c'] and values = [30, 10, 20], zip them into a list of tuples sorted by v - medium
• Given letters = ["a", "c", "d", "e"], insert "b" at index 1 - medium
• Given letters, build a dictionary called freq that maps each character to how many times it appears - medium
• Given monday = {'ada', 'linus', 'grace'} and tuesday = {'linus', 'grace', 'margaret'}, print the sor - medium
• Given name = 'ada lovelace', print the result of name.title() - medium
• Given name and age, use an f-string to print exactly: My name is Alex and I am 25 years old. - medium
• Given name = 'Grace' and score = 97, use an f-string to print 'Grace scored 97 (perfect)' when score - medium
• Given names = ['Ada', 'Linus', 'Grace'] and scores = [95, 82, 91], use zip and enumerate (starting a - medium
• Given names and scores, use zip() to pair them and print each pair in the format 'name: score', one - medium
• Given names, use a for loop to build a new list called upper_names containing each name converted to - medium
• Given nested = [[1, 2], [3, 4, 5], [6]], flatten it into a single list using a list comprehension - medium
• Given nested = {'team_a': [1, 2, 3], 'team_b': [4, 5]}, use a dict comprehension to build a new dict - medium
• Given number = 14, print 'even' if number % 2 == 0, otherwise print 'odd' - medium
• Given nums = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9], print every other item starting from index 0 using a st - medium
• Given nums = [1, 2, 2, 3, 3, 3, 4, 4, 4, 4], use a dict to count occurrences in a single pass (O(n)) - medium
• Given nums = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10], build a list of squares of even numbers using a list c - medium
• Given nums = [1, 2, 3, 4, 5, 6, 7, 8], use filter and a lambda to keep only odd numbers, then print - medium
• Given nums = [1, 2, 3, 4, 5, 6], build a list of squares of even numbers using a list comprehension - medium
• Given nums = [1, 2, 3, 4, 5, 6], use any() to check if any element is > 5 (print result), then use a - medium
• Given nums = [1, 2, 3, 4, 5, 6], use filter with a lambda to keep only even numbers, then map with a - medium
• Given nums = [1, 2, 3, 4, 5], use functools.reduce with a lambda and an initial value of 1 to comput - medium
• Given nums = [1, 2, 3, 4, 5], use map and a lambda to square each number, then list() the result - medium
• Given nums = [1, 2, 3, 4, 5], write an O(n^2) pair sum that prints every i + j where i and j are dis - medium
• Given nums = [1, 2, 3], append 4 to the list without assigning the result - medium
• Given nums = [12, 5, 23, 8, 17], print the minimum, the maximum, and the sum, each on its own line. - medium
• Given nums = [1, 3, -2, 5, -1, 4, 6] and window = 3, compute the maximum sum of any 3 consecutive el - medium
• Given nums = [2, 7, 11, 15] and target = 9, find the two indices whose values sum to target using a - medium
• Given nums = [3, 1, 4, 1, 5, 9, 2, 6, 5, 3], print the number of unique values - medium
• Given nums = [3, 1, 4, 1, 5, 9, 2, 6], compute the prefix sum list where prefix[i] = sum(nums[:i+1]) - medium
• Given nums = [3, 7, 2, 8, 5], use a list comprehension with the walrus operator to capture only elem - medium
• Given nums = [4, 1, 5, 2, 7, 3, 6], use sorted() (which is O(n log n)) to sort them ascending and pr - medium
• Given nums = [4, 1, 7, 2, 9, 3, 8, 5, 6], print the top 3 values sorted descending using slicing on - medium
• Given nums = [4, 7, 2, 9, 3, 8], filter to only even numbers, then sum those - medium
• Given nums = [5, 2, 9, 1, 7, 3, 8], use heapq.nlargest to print the top 3, then heapq.nsmallest to p - medium
• Given nums = [8, 3, 5, 1, 9, 2, 7], use a lambda with sorted() to sort by the absolute difference fr - medium
• Given nums, use a for-else loop to search for the first negative number - medium
• Given nums, use a for loop to calculate the sum of all numbers - medium
• Given nums, use a for loop to count how many values are greater than 5 - medium
• Given nums, use a for loop with break to find the first negative number and print it - medium
• Given nums, use a for loop with continue to skip negative values - medium
• Given n, use a for-else loop to check if n is prime - medium
• Given n, use a while loop to count down from n to 1, printing each number on its own line - medium
• Given op = 'add', x = 10, y = 4, use a dict that maps 'add', 'sub', 'mul', 'div' to lambdas - medium
• Given original = [10, 20, 30], create an independent copy using .copy() and store it in a variable c - medium
• Given pairs = [('ada', 95), ('linus', 82), ('grace', 91), ('margaret', 78)], filter to scores >= 90 - medium
• Given password_length, store whether the password is long enough (>= 8 characters) in a variable cal - medium
• Given path = '/home/user/report.csv', print True if path endswith '.csv' and False otherwise - medium
• Given payload = {'user': 'ada', 'scores': [10, 20, 30], 'meta': {'active': True}}, convert it to a J - medium
• Given planets = ["Mercury", "Venus", "Earth", "Mars"], print the third planet using index 2, then pr - medium
• Given price and discount, subtract the discount from the price and print the result. - medium
• Given price, apply a $5 discount by subtracting 5 from price - medium
• Given prices = [5, 10, 15, 20, 25], loop through each price and append it to a new list called doubl - medium
• Given prices = {'apple': 2, 'banana': 1, 'cherry': 4}, iterate over .items() and print a line like ' - medium
• Given raw = ' Ada Lovelace ', strip whitespace, replace spaces with underscores, and print the res - medium
• Given raw = 'apple, banana , cherry,grape', split on comma, strip each piece, and print the cleaned - medium
• Given raw_tags = ['py', 'sql', 'py', 'go', 'sql', 'py'], build a dict called counts where each key i - medium
• Given raw = ['x', 'y', 'z', 'x', 'y'], build a set from raw and store it in unique - medium
• Given readings = [3.1, -2.4, 5.0, -1.8], compute the sum of absolute values using abs() in a loop - medium
• Given records = [('a', 1), ('b', 2), ('a', 3), ('b', 4), ('a', 5)], group values by key into a dict - medium
• Given records = [('a', 1), ('b', 2), ('a', 3), ('b', 4), ('a', 5)], use collections.defaultdict(list - medium
• Given records = [('Ada', 36), ('Linus', 54), ('Grace', 85)], loop through records and print a line l - medium
• Given required = {'python', 'sql'} and have = {'python', 'sql', 'go'}, print True if required is a s - medium
• Given result and value, use the 'is' operator to check if each variable is None - medium
• Given rows = [[1, 2], [3, 4], [5, 6]], iterate with nested loops to build a list called flat - medium
• Given score = 73, print 'excellent' if score >= 90, 'good' if score >= 75, 'pass' if score >= 60, ot - medium
• Given score = 78, use a ternary expression to assign label = 'pass' if score >= 70 else 'fail' - medium
• Given score, increase it by 15 and print the new value. - medium
• Given scores = [88, 92, 75, 95, 83, 90, 87], print the last 3 scores using a negative-index slice - medium
• Given scores (a dictionary of name:score pairs), use a for loop with .items() to print only the name - medium
• Given score, use if/elif/else to assign a letter grade: "A" if score >= 90, "B" if >= 80, "C" if >= - medium
• Given seen_users = frozenset({'ada', 'linus', 'grace'}), try to add a user (this would fail on a mut - medium
• Given settings = {'theme': 'dark', 'font_size': 14} - medium
• Given sorted_nums = [1, 2, 4, 5, 7, 9, 11] and target = 9, use the two-pointer technique to determin - medium
• Given sorted_nums = [1, 3, 7, 12, 18, 25, 33, 40, 55, 68, 82], implement O(log n) binary search for - medium
• Given sorted_nums = [1, 4, 7, 12, 18, 23], use bisect.insort to insert 10 - medium
• Given stack = ["first", "second", "third", "fourth"], use pop() with no argument to remove and print - medium
• Given start, use a while loop to double start repeatedly until it is greater than or equal to 100 - medium
• Given status = 'error', print 'ok' for 'success', 'retry' for 'pending', 'stop' for 'error', and 'un - medium
• Given students = [('Ada', 95), ('Linus', 82), ('Grace', 91)], use enumerate to print a line like '1 - medium
• Given tasks, use enumerate() with start=1 to print a numbered task list - medium
• Given temperature = 72, print 'comfortable' if 65 <= temperature <= 75, otherwise print 'uncomfortab - medium
• Given temperature, print whether temperature equals 100 using the == operator. - medium
• Given temperature, print whether temperature is greater than or equal to 70 on the first line, then - medium
• Given temps = [72, 68, 75, 80, 85, 78, 70, 73], use slicing to extract items at indices 2 through 5 - medium
• Given the `book` dictionary, print the title and the year on separate lines. - medium
• Given the `colors` dictionary, check if the value "blue" exists among the dictionary's values and pr - medium
• Given the `contact` dictionary, check if the key "phone" exists and print the result - medium
• Given the decimal string score_text, convert it to an integer by first converting to float, then to - medium
• Given the integer count, build a message by concatenating "Found " + the count converted to a string - medium
• Given the `inventory` dictionary, use .pop() to remove the key "banana" and store the removed value - medium
• Given the list [1, 2, 2, 3, 3, 3, 4], use a frequency dict to find all elements that appear more tha - medium
• Given the list `fruits`, use a dictionary called `counts` to count how many times each fruit appears - medium
• Given the list items, convert it to a set to find the unique values - medium
• Given the list numbers, use a list comprehension with a ternary expression to create a list called s - medium
• Given the list nums, use extended unpacking to capture the first element in 'first', the last elemen - medium
• Given the list of coordinate pairs (as lists) called points, convert each inner list to a tuple and - medium
• Given the list page_views, use a set to count how many unique pages were viewed - medium
• Given the list temps representing daily temperatures, find and print the lowest temperature, the hig - medium
• Given the list valid_codes as a list, convert it to a set called valid_set - medium
• Given the list 'values', loop through each and print "T" if the value is truthy or "F" if it is fals - medium
• Given the list words and the dictionary config, print the length of each on its own line - medium
• Given the `server` dictionary, print the host and port values on separate lines. - medium
• Given the set animals, remove 'cat' using .remove() - medium
• Given the set fruits, use .update() to add all items from the list new_fruits - medium
• Given the `settings` dictionary, use `del` to remove the "debug" key - medium
• Given the string age_text, convert it to an integer using int() - medium
• Given the tuple record containing a name, age, and job title, unpack it into three variables: name, - medium
• Given the tuple scores, calculate the average by dividing sum() by len() - medium
• Given the `user` dictionary, add a new key "city" with value "Denver" - medium
• Given the variable language, use an f-string to print exactly: I am learning Python - medium
• Given the variable score, reassign it to 95 and print the updated value. - medium
• Given the variable temperature, write an if/elif/else chain: print "Hot" if temperature is 30 or abo - medium
• Given tokens = ['2026', '04', '22'], join them with '-' to build a date string - medium
• Given total_minutes = 275, use divmod to split it into hours and minutes in one expression - medium
• Given total_minutes, use floor division (//) to calculate whole_hours and modulo (%) to calculate re - medium
• Given total_seconds = 305, compute minutes as total_seconds // 60 and seconds as total_seconds % 60 - medium
• Given two lists a = [1, 2, 3, 4, 5] and b = [3, 4, 5, 6, 7], find common elements in O(n + m) using - medium
• Given two point values point_a and point_b, calculate the absolute distance between them using abs() - medium
• Given user = None and default_name = 'guest', use the or operator to assign name = user or default_n - medium
• Given users = [{'name': 'Ada', 'age': 36}, {'name': 'Linus', 'age': 54}, {'name': 'Grace', 'age': 85 - medium
• Given vals = [42, 17, 93, 8, 56], use the sorted() function to create a new sorted list called sorte - medium
• Given value = None, print True if value is None, then print False if value is not None - medium
• Given values = [3, 8, 1, 9, 4, 7], print the average as a float - medium
• Given words = ['apple', 'banana', 'cherry', 'avocado', 'grape', 'date'], build a set comprehension o - medium
• Given words = ['apple', 'bat', 'cherry', 'date'], build a dict where each key is the word and each v - medium
• Given words = ['apple', 'bat', 'cherry', 'date', 'elderberry'], count how many have length 5 or more - medium
• Given words = ["banana", "fig", "apple", "cherry"], use sorted() with key=len and reverse=True to so - medium
• Given words = ['cherry', 'apple', 'fig', 'banana'], sort them by length ascending, breaking ties alp - medium
• Given words = 'the quick brown fox jumps over the lazy dog the fox'.split(), use collections.Counter - medium
• Given words, use enumerate() to find the indices of all words that have more than 4 characters - medium
• Given x and y, check if x is greater than y and print the result. - medium
• Given x and y (integers) and a and b (strings), print x + y on one line and a + b on the next to see - medium
• Given x (set to None), print the result of x == 0 on the first line and x is None on the second line - medium
• Greeting Formatter Class - easy - First impressions are formatted carefully.
• Group Average - hard - Same group, different values. What is typical?
• Group By - medium - Same key, different rows. Bring them together.
• Group the items by category using dict.setdefault() - medium
• Implement a simple traffic light state machine using a dictionary - medium
• Implement a sliding window to find the maximum sum of any 3 consecutive numbers in the list [2, 1, 5 - medium
• Implement memoized Fibonacci using a dictionary cache - medium
• Implement the two_sum function using a dictionary - medium
• Import bisect - medium
• Import copy and create a deep copy of original = [[1, 2], [3, 4]] - medium
• Import copy and use deepcopy to create an independent copy of original = {'name': 'Alice', 'scores': - medium
• Import heapq - medium
• Import json - medium
• Insert 'd' into the LRU cache, then evict the least-recently-used entry using popitem(last=False). - medium
• Iterate over range(1, 11) - medium
• Iterate over the list [10, 20, 30, 40, 50] in reverse using reversed() - medium
• Join the letters list with no separator to form a word - medium
• Join the path_parts list into a Unix-style file path using "/" as the separator - medium
• Lag Column - medium - What came before this row?
• Left Join - medium - Keep the left side. Match what you can.
• Loop through settings using .items() and print each key-value pair in the format "key -> value", one - medium
• Loop through the metrics dictionary using .items() and print each entry in the format 'key: value%' - medium
• Loop through the ops dictionary, call each function with 5, and print the operation name and result. - medium
• Majority Event in Stream - medium - One event type is drowning out the rest. Find it without a frequency table.
• Make a deep copy of original, modify the copy's first sublist, and confirm the original is unchanged - medium
• Map each workload to the right execution model - medium
• Max Length Token - medium - The longest token wins.
• Merge Counters - medium - Two tallies. Combine them.
• Merge Intervals - hard - Overlapping ranges. Merge them.
• Merge Overlapping Time Ranges - medium - Intervals piling up. Clean the timeline.
• Model why async helps I/O-bound work - medium
• Normalize Name - easy - Names are messy. Standardize them.
• No Shortcuts - easy - The peak value. Built-ins off the table.
• Null Counter - easy - How many holes in the data?
• Ordered Character Check - easy - Check if all As appear before all Bs.
• Palindrome Hunt - medium - It reads the same both ways. Go further.
• Parse Log Line - medium - One line. A dozen fields hidden inside.
• Parse the log entry by splitting on ":" with maxsplit=2 to extract exactly 3 parts: the level, the t - medium
• Permissions Manager - medium - Manage user permissions with config updates.
• Pivot Records - hard - Long format is easy. Wide format is useful.
• Portfolio Profit Calculator - medium - Portfolio gain from purchase history and current prices.
• Precision and Recall - medium - Precision and recall. Both matter.
• Prefix Based Word Replacement - medium - Every word trimmed to its root.
• Print event totals from most_common() as a dict, then print each user's actions sorted by user id. - medium
• Progress Milestones - easy - Progress at every 10% increment. Keep the receipts.
• Quality Gate - easy - Not everything passes inspection.
• Quantile Calculator - easy - Mark the boundary value at a given point.
• Rank Metrics - medium - Not all numbers are equal. Rank them.
• Every Line on the Receipt - medium - Nested deep inside the receipt. Pull every item out.
• Record Filter - easy - Some records belong. Others do not.
• Rename Keys - medium - Old names out. New names in.
• Replace an if/elif chain with dict-based dispatch - medium
• Retrieve 'result_data' from the dict using k2 (an identical but separate instance from k1) as the ke - medium
• Reverse Field - easy - Flip it. See what happens.
• Rotate Buffer - medium - The buffer is full. Rotate it.
• Row Aggregates - medium - Each row holds its own summary.
• Run Length Encoding - easy - AAABBB becomes 3A3B. Compress it.
• Running Distinct Count - medium - New values keep appearing. Track the count.
• Safely delete keys from a dict during iteration - medium
• Safely remove all even numbers from the list [1, 2, 3, 4, 5, 6, 7, 8] by iterating over a copy (list - medium
• Sanitize Field - easy - Dirty input. Clean output.
• Schema Checker - easy - The schema says one thing. The data says another.
• Sequential Word Pairs - easy - Everything has a neighbor.
• Set counter = 0 at the module level - medium
• Set x = 100 at the module level - medium
• Shortest Unique Metric Tag - medium - One token per metric. Make it unambiguous.
• Show that .copy() is shallow: create original = {'items': [1, 2, 3]}, make a shallow copy with .copy - medium
• Show that frozenset operations return new frozensets - medium
• Show that sort() returns None - medium
• Show the multiplication trap: create wrong = [[0] * 3] * 3, set wrong[0][0] = 1, and print wrong - medium
• Show the mutable default argument bug: write a function add_to(item, bag=None) that safely creates a - medium
• Simplify boolean expressions - medium
• Single Element Among Pairs - easy - One element has no partner.
• Sort Descending - easy - Biggest first. No exceptions.
• Sort the employees list by salary in descending order using sorted() with a lambda as the key - medium
• Sort the employee tuples by department ascending, then by salary descending within each department - medium
• Sort the list [4, 2, 7, 1, 3, 7, 2] and find all duplicates by comparing adjacent elements - medium
• Sort the list of student tuples by their score (the second element) using sorted() with a lambda key - medium
• Sort the list of words by their length (shortest first) using sorted() with a key function - medium
• Sort the scores in descending order and print only the top 3 scores using slicing. - medium
• Sort the students by grade ascending, then by score descending (highest first), then by name ascendi - medium
• Split the CSV header on ',' and rejoin with tabs - medium
• Split the multiline text into individual lines using splitlines() - medium
• Start with all_tasks and use the - operator to remove completed and blocked tasks in a chain - medium
• Start with an empty list called doubles - medium
• Start with an empty list called nums - medium
• Start with an empty set called colors - medium
• Start with count = 1 - medium
• Start with inventory = {'apple': 3, 'banana': 5, 'cherry': 7} - medium
• Start with items = ['apple', 'banana'] - medium
• Start with seen = set() - medium
• Start with tags = {'python', 'sql', 'go', 'rust'} - medium
• Start with tasks = ['email', 'meeting', 'lunch', 'review'] - medium
• Stock Range Finder - medium - Prices move. One stretch had the widest gap.
• Store the result of calling get_message() (with parentheses) in result2 - medium
• Store three functions in a list: one that adds 1, one that doubles, one that squares - medium
• Stream-Process a Large CSV - hard - Too big to load. Read what you can.
• Strip whitespace from raw, replace 'World' with 'Python', and print the result and its length. - medium
• Subarray Signal - medium - One stretch carries the strongest signal.
• Swap the values of x and y using only arithmetic (addition and subtraction) with no temporary variab - medium
• The Account Manager - easy - Deposits, withdrawals, and the risk of going negative.
• The Additive Chain - easy - Each value is the sum of the two before it - no calls to itself allowed.
• The Address Surgeon - easy - One string hides a street, a city, a state, and a zip.
• The Alphabet Score - easy - Every letter has a secret numeric value - what's your total?
• The Alphabet Sorter - easy - Filing cabinet logic: everything goes in its proper drawer.
• The Anomaly Detector - hard - Spot the outliers before they page someone.
• The Balanced Inspector - medium - Every branch should carry the same weight.
• The Balanced Sum - easy - Some numbers have a rare quality that mathematicians revere.
• The Bipartite Test - medium - Can this crowd be split into two perfectly separated groups?
• The Bit Counter - easy - How many lights are on in the binary representation?
• The Bit Ladder - easy - Count the ones all the way up.
• The Bit Reverser - medium - Sometimes the answer is literally backwards.
• The Bitwise Judge - easy - No division, no modulo - just a single bit tells you everything.
• The Blind Multiplier - medium - Compute the result of everything around you - without seeing yourself.
• The Bonus Round - medium - Consecutive matching dice rolls trigger a special scoring rule.
• The Bouncer - easy - Every door has a guest list.
• The Bracket Validator - easy - Brackets opened and closed. The nesting might be off.
• The Bronze Medalist - easy - Not first, not last - somewhere in the middle of the podium.
• The Budget Allocator - medium - Split the money. Some wore two hats.
• The Bug Spotter - easy - It compiles. The answer is still wrong.
• The Build Order - medium - Some tasks must wait for others to finish first.
• The Calendar Sort - easy - Time has its own opinion about order.
• The Carousel - easy - Keep moving, same ride.
• The Category Ranker - medium - Categories have standing. Rows get theirs.
• The Chain Builder - medium - Links connect in sequence - build the chain from scratch.
• The Chain Transform - medium - One small step at a time can cover a great distance.
• The Change Data Capture - hard - Inserts, updates, deletes : all present.
• The Change Tracker - medium - Before and after snapshots. The delta is in there.
• The Character Clans - medium - Words sharing the same letters belong to the same clan.
• The Character Encoder - easy - Squeeze a string down to its tightest form.
• The Character Map - easy - Character-level frequency. As a dictionary.
• The Chunked Reader - medium - Too big for memory. Read in pieces.
• The Cipher Wheel - easy - Every letter has an alias - you just need the right codebook.
• The Clock Angle - easy - Two hands. One gap. One number.
• The Clock Examiner - medium - Two hands on a clock - how wide is the gap?
• The Code Expander - easy - Compressed messages need a decoder to come alive.
• The Coin Vault - medium - Exact change only - and you want to use as few coins as possible.
• The Column Shuffle - medium - Rows in, columns out. Number them.
• The Column Transformer - easy - Each column gets its function.
• The Column Zipper - easy - Headers on top, values below, dict in the middle.
• The Complement Hunt - easy - Every number is looking for its other half.
• The Config Blender - easy - Config collision. The surviving values after a merge.
• The Consecutive Sequence Finder - medium - Numbers that flow without interruption.
• The Consecutive Streak - medium - Login streaks. No gaps allowed.
• The Counting Machine - medium - It knows where it stopped last time.
• The Crowd Favorite Eatery - easy - One restaurant clearly won the most hearts.
• The Crowd Pleaser - easy - One value shows up more than all others combined.
• The Crowd Splitter - easy - The middle holds even with a dominant outlier.
• The Custom Iterator - medium - Some sequences follow their own rules.
• The Cycle Detector - medium - Follow the chain long enough and you might end up where you started.
• The DAG Executor - hard - Wire up a mini pipeline and watch it run.
• The data dict has a "user" key with a nested dict containing "name", but no "email" key - medium
• The Date Sorter - medium - Jumbled calendar. Sort it first.
• The Decomposer - easy - Every composite thing can be broken down to its simplest parts.
• The Deep Config - medium - Nested config, dot-notation output.
• The Deep Dictionary - easy - One key goes further than the rest.
• The Deep Dive - easy - A specific position in the unsorted pile.
• The Deep Selector - easy - Tell it what you want. It knows where to look.
• The Deep Unpacker - easy - Boxes inside boxes. Eventually you reach the bottom.
• The Dependency Resolver - medium - Everything depends on everything.
• The Depth of Field - easy - Some containers hold containers that hold containers.
• The Diagonal Accountant - easy - Two diagonals cross in the center of every square.
• The Dict Comparator - medium - Two dictionaries. Subtle differences.
• The Dictionary Inverter - easy - Flip the dict. Group what used to be values.
• The Dominant Signal - easy - Hottest items in the transaction log. Ties included.
• The Double-Ended Gateway - medium - Some queues let you skip the line from both ends.
• The Duplicate Spotter - easy - Some values appear more than once - report only those.
• The Dynamic Container - hard - Build your own resizable list with no help from the standard library.
• The Elevator Trace - medium - Nested floors. One path through.
• The Email Ranker - medium - Some inboxes see more action.
• The Encoded Signal - medium - The encoding is hiding multipliers. Decode it.
• The Even Checkpoint - easy - Is this number in the even club? Prove it the fast way.
• The Event Aggregator - medium - Bucket a firehose of events into tidy time windows.
• The Event Broadcaster - medium - Subscribers show up, listen, and sometimes leave.
• The Event Bucketer - easy - Logs slotted into buckets.
• The Event Overlap Detector - medium - Overlapping events. The calendar knows.
• The Event Window - medium - A five-minute window is all that matters.
• The Eviction Policy - medium - Fixed capacity. Oldest unused entry gets evicted.
• The Exception Handler - medium - Good code handles failure as gracefully as success.
• The Expander - easy - What goes in small comes out big.
• The Face That Breaks the Bank - medium - Roll enough dice and one number always runs away with it.
• The Family Reunion - medium - Two cousins share a common ancestor somewhere above.
• The Fast Climber - medium - Some routes up the mountain are faster than others.
• The Field Counter - easy - Some fields speak louder than others.
• The File Size Profiler - medium - File types and their disk footprint. One type dominates.
• The File Tree Builder - medium - Flat paths. Build the nested tree.
• The First Class Function - medium - Functions travel as values - prove you can pass one around.
• The First Encounter - easy - Every character has a story - but only if you remember where it started.
• The First Stranger - easy - In a crowd, the unique ones stand out first.
• The Flat Mapper - medium - Nested values. One flat stream out.
• The Forbidden Ceiling - easy - Round up. But not the obvious way.
• The Forbidden Sorter - medium - Put the letters in order without the obvious tool.
• The Forgetful Machine - medium - It remembers everything, until it does not.
• The Forward Fill - easy - Patch the gaps in a noisy sensor stream.
• The Frequency Eviction - hard - When storage is tight, something has to go.
• The Gap Filler - easy - Fill the Nones with the last real value.
• The Gap Reporter - medium - The missing IDs in the log - somebody has to notice.
• The Gate Keeper - easy - Not all openings have a closing.
• The Generous Ones - medium - The generous ones are obvious.
• The Genre Filter - medium - Three tables, two conditions, one actor's total.
• The Grid Pivot - easy - A different angle reveals a completely different picture.
• The Half-Life Search - medium - Every guess cuts the problem in half.
• The Halftime Score - easy - Middle value of a dataset. No built-in shortcuts.
• The Hash Stamper - easy - One input, one irreversible output - the foundation of every secret.
• The Hierarchy Builder - hard - Parent-child pairs, flat. Build the family tree.
• The High Mark - easy - Scan the list. Report the max.
• The High Rollers - medium - Not every gambler bets the same - some wager far more than others.
• The Horizon Scanner - medium - For each position, what is coming up ahead?
• The Hostile Takeover - medium - One dict eats another.
• The Host Ranker - medium - Some hosts have more to offer.
• The Hourly Bucket - medium - Timestamps belong somewhere.
• The Impersonator - medium - You only have stacks. Make a queue anyway.
• The Indivisibles - easy - Numbers that yield only to themselves.
• The Infection Spread - hard - It starts with one, and then it spreads.
• The Integer Sieve - easy - Not everything in this list belongs here.
• The Intervals - medium - Timestamps in buckets.
• The Inverted Triangle - medium - A pattern of stars narrows toward the bottom.
• The IP Validator - easy - Real and fake, mixed together.
• The Island Counter - medium - Surrounded by water, connected by land - how many separate landmasses?
• The Last Instance - easy - When duplicates appear, only the last one counts.
• The Last Seen Map - easy - For each character, where did it appear last?
• The Lazy Squares - easy - A sequence that never fully reveals itself.
• The Lazy Stream - hard - Yield values one at a time from a potentially infinite source.
• The Lazy Unpacker - medium - Instead of loading it all at once, yield it one piece at a time.
• The Letter Census - easy - Every crowd has its share of talkers and quiet ones.
• The Letter Frequency Map - easy - Count every character in the string and report the results.
• The Letter Kin - medium - Words that share the same letters belong together.
• The Letter Ledger - easy - Every character has a count to answer for.
• The Letter Mapper - medium - A consistent substitution, or not.
• The Letter Tally - easy - Each character in the string has a count to answer for.
• The Level Inspector - medium - Each floor of the tower tells a different story.
• The Level Summer - medium - Add up each level of the tree.
• The Line Cutter - easy - Did everyone with an A-pass get through before the B-crowd arrived?
• The Line Splitter - easy - Comma-separated truths, one at a time.
• The Link Shrinker - medium - Long addresses have aliases - you give them out, you keep the map.
• The List Merger - easy - No shortcuts.
• The Load Balancer - medium - Distribute incoming requests evenly across available servers.
• The Log Decoder - easy - Every line holds a secret.
• The Log Pulse - easy - Some lines repeat themselves.
• The Lone Character - easy - It appeared exactly one time. That made it special.
• The Lone Traveler - easy - One character stands apart from the crowd.
• The Manual Sorter - easy - No shortcuts, no built-ins, just work.
• The Map Reducer - medium - Map it. Reduce it. One answer.
• The Market Streak - medium - Some stocks run longer than you think.
• The Market Timer - medium - One buy, one sell - when do you make the most?
• The Matching Manifest - easy - Two warehouses, one shipment - only load what's in both.
• The Median Keeper - hard - The middle value keeps moving as new data arrives.
• The Meeting Room Allocator - hard - Meetings overlap on the calendar. Rooms are limited.
• The Merge - easy - Chaos in. Order out.
• The Merge Champion - medium - Many sorted rivers flowing into one.
• The Messy Pipeline - easy - The upstream API has no idea what a schema is.
• The Middle Ground - hard - The middle value keeps moving.
• The Min Tracker - medium - The stack remembers the best it ever saw.
• The Minutes Tracker - easy - Some activities eat more time than others.
• The Mirror Flip - easy - Sometimes the fastest fix is to swap everything.
• The Mirror Image - easy - Flip the tape backwards - start from the end.
• The Mirror Test - easy - Check if a string reads the same forwards and backwards.
• The Mirror Words - easy - Each word looks back at itself.
• The Missing Number - easy - Something is missing from the sequence.
• The Molecule Report - easy - Four letters. A lot of math hidden in the sequence.
• The Month-by-Month Snapshot - medium - Every salesperson has a story. The months just tell it sideways.
• The Mountain Peak - medium - The sequence has a summit.
• The Multiplication Trail - easy - Each step multiplies the whole journey.
• The Multiplier Rush - medium - Negatives cancel negatives - but only if you keep both in view.
• The Narrow Lens - medium - A narrow timeframe. Everything inside matters.
• The Nearest Value Mapper - medium - Close enough counts. Ties go low.
• The Never-Ending Sequence - easy - Sequence that keeps going. Follow it.
• The Numbered Chair - easy - A standing list. Position n holds one entry.
• The Number Miner - medium - JSON strings are hiding numeric secrets - dig them out.
• The Number Narrator - medium - Every number has a story in words.
• The Number Screen - easy - Some numbers make the cut. Most do not.
• The Odd Digits - easy - Hidden inside a mess of characters are a few odd numbers.
• The Odd Extractor - easy - Not all numbers from a string are welcome here.
• The Odd Filter - easy - Strip out everything that does not belong to the odd club.
• The One-of-Each - easy - Strip the repeats, keep the originals.
• The One-Timers - easy - Values that never repeated.
• The One-Way Street - easy - Monotonic time-series. Direction only.
• The Onion Layer - hard - Peel from the outside in - one ring at a time.
• The Online Elite - medium - The top performers are hiding in the data.
• The OOP Pillars Exam - medium - Four principles, one class hierarchy - show you know all of them.
• The Op Dispatcher - easy - Name the operation, apply it everywhere.
• The Order Enforcer - easy - Some rules say every A must come before every B.
• The Order Inspector - medium - A binary tree has rules - is this one actually following them?
• The Original Keeper - easy - Clean up duplicate events without losing the timeline.
• The Output Peak - hard - One stretch outpaced all the others.
• The Overlap Finder - easy - Two guest lists - who made it onto both?
• The Page Turner - medium - Nobody loads everything at once.
• The Pair Counter - easy - How many pairs can be formed from the crowd?
• The Paired Doors - easy - Every open bracket has a partner - but not every partner shows up.
• The Pandas Pivot - medium - Rows become columns. Columns become power.
• The Parentheses Factory - medium - Building balanced brackets is an art form.
• The Pascal Row - easy - Each number is the sum of two numbers above it.
• The Password Builder - easy - Random characters, fixed rules.
• The Password Forge - easy - Does this password pass the strength gate?
• The Pay Ladder - medium - Climb the ladder the hard way. No shortcuts allowed.
• The Payload Flattener - medium - Turn a deeply nested API response into a flat row.
• The Peak Finder - easy - Largest number in the list. Max() is not an option.
• The Perfect Match - medium - Two numbers walk into an interview...
• The Pipeline Filter - easy - In the door as one thing, out the door as another.
• The Placement Fixer - medium - Each value belongs in exactly one spot.
• The Postfix Processor - medium - Math without parentheses - the operators come after the numbers.
• The Precision Hunt - medium - Some answers need no decimal point.
• The Price Bander - easy - Different prices, different treatment.
• The Priority Queue - medium - When two things tie, something has to break the deadlock.
• The Progress Meter - medium - Report progress at every tenth of the way through.
• The Progress Parade - easy - Just tell them how far along you are.
• The Quarter Turn - medium - One rotation changes everything.
• The Queue Disguise - medium - A queue in sheep's clothing.
• The Ranked Dict - easy - Values deserve order too.
• The Record Reconciler - medium - Two versions of the same truth.
• The Repeat Offenders - easy - Repetition is a clue.
• The Repeat Review - medium - The echo came back.
• The Repeat Visitor - medium - Loyal customers come back sooner than expected.
• The Response Aggregator - medium - Multiple result pages. One clean summary.
• The Resume Sifter - medium - Pull what's useful. Skip what you know.
• The Rolling Peak - medium - The sweetest stretch in the sequence.
• The Rolling Window - medium - Smooth things out, one step at a time.
• The Roman Converter - easy - Roman numerals decoded.
• The Rotated Array - medium - Someone shuffled it. Now locate what you came for.
• The Runner-Up - easy - Not the winner. The one just behind it.
• The Running Total - easy - Each position holds the sum of everything before it.
• The Safe Caster - easy - Type conversion is easy, until it is not.
• The Schedule Cleaner - medium - Overlapping sessions. One clean line.
• The Schema Diff - medium - Two versions of the same config - what changed between them?
• The Schema Differ - medium - Schema from yesterday vs today. Something changed.
• The Schema Migrator - hard - Old schema in, new schema out.
• The Scoreboard Race - medium - Simulate rounds until someone hits the target.
• The Score Sorter - easy - Points on the board, sorted by who earned the most.
• The Scramble Check - easy - Same letters, different order - are these two strings secret twins?
• The Second Summit - easy - Not the top of the mountain - just below it.
• The Secret Twins - easy - Same letters, different disguises.
• The Self-Portrait Number - easy - Some numbers describe themselves perfectly.
• The Sequel Spotter - easy - Spot the sequels hiding in the catalog.
• The `settings` dictionary has no "theme" key - medium
• The Shadow Cleaner - easy - Remove the repeats. No shortcuts.
• The Shifting Standard - medium - A benchmark in motion.
• The Short Address - medium - Turn a big number into a compact alphanumeric code.
• The Shortest Route - medium - Fewer hops is always better.
• The Silent Locator - easy - Every lookup should cost you less than the one before it.
• The Silver Screen Summit - medium - Box office totals decide who makes the top of the marquee.
• The Single Bit - easy - One particular pattern hides in plain sight.
• The Slow Leak - medium - Nested iterators. One flat stream.
• The Sneaky Twins - medium - They look different but they are the same inside.
• The Social Graph - easy - Everyone knows someone.
• The Solo Act - easy - One-and-done values only.
• The Spin Doctor - medium - Ninety degrees, but which way?
• The Spiral Harvest - medium - The snail reads the grid in its own special order.
• The Spread - easy - Data spread around a center. The range matters.
• The Squeeze - easy - aaabbb gets old fast. Shrink it.
• The Staircase Problem - medium - One step or two, the choices add up.
• The Status Board - medium - Make sense of a pile of raw Nginx access logs.
• The Step Counter - easy - You can hop one step or two - how many ways to reach the top?
• The Streak Breaker - easy - It has a problem with repetition.
• The Stream Averager - easy - The answer moves with the data.
• The Stream Joiner - hard - Events don't wait for each other. This does.
• The String Shrinker - easy - Compress the string. Shorter wins.
• The Style Guide - easy - Not every word deserves the same treatment.
• The Subarray Tally - medium - How many hidden windows hit the target?
• The Syntax Sentinel - easy - Brackets opened and closed. The nesting might be off.
• The Table Thief - medium - Somewhere in that query, tables are hiding.
• The Tag Analyst - medium - Two sets of labels, one analysis.
• The Tail End - easy - Push, pop, peek. The basics that break people.
• The Tail Finder - medium - Navigate to the end of a linked list using recursion.
• The Tail Trimmer - easy - Remove the k-th item from the back without counting forward first.
• The Tally Counter - easy - How many times does a single guest show up to the party?
• The Target Hunt - medium - Pairs that hit a target. Every one of them.
• The Throttle Ceiling - medium - Too many requests in too short a timeframe. Throttle it.
• The Throttle Wall - hard - Stop the abusers. Let the rest through.
• The Timezone Trap - medium - Trip data and timezones. They're not the same thing.
• The Timing Decorator - medium - Wrap any function to capture how long it takes.
• The Title Ladder - medium - Job titles and the salary tier they belong to.
• The Top Reviewer - easy - One restaurant receives the most feedback - which one?
• The Top Words - medium - In every document, some words dominate the conversation.
• The Trade Log Aggregator - medium - Every trade left a footprint.
• The Trade Signal - easy - Buy low, sell high. Identify the ideal moment.
• The Traffic Director - easy - Spread the load evenly - nobody should be doing all the work.
• The Trapped Pool - hard - What collects in the valleys after the rain?
• The Tree Measurer - easy - How deep does the rabbit hole go?
• The Trip Aggregator - medium - Travel records hold patterns waiting to be surfaced.
• The Trip Grouper - easy - Where did everyone go, and for how long?
• The Triple Alliance - hard - Three numbers, one target.
• The Triplet Hunt - medium - Every path that works gets a seat at the table.
• The Type Sorter - easy - A mixed list is hiding its numbers - extract them.
• The user dict has no "role" key - medium
• The Value Sorter - easy - The order was always negotiable.
• The variable count holds the integer 5 - medium
• The variable `number` holds an integer - medium
• The variable phrase holds a string - medium
• The variable price_text holds the string "30" - medium
• The variable raw_name holds a messy name string - medium
• The variable reply holds user input in mixed case - medium
• The variables item and qty are provided - medium
• The variable username holds a string - medium
• The variable word holds "python" - medium
• The Velvet Rope - medium - Some users get in. Others wait outside until the window resets.
• The Version Parade - easy - 1.0 before 2.0. Don't let the dots confuse you.
• The Version Ranker - medium - Software versions follow their own ordering rules.
• The Vocabulary Test - medium - Can you spell out the whole sentence using only the words you know?
• The Vowel Hunt - easy - Just the vowels. All of them.
• The Waiting Game - medium - Patience has a price - and a count.
• The Water Collector - hard - Two walls, one sky, and a very important question.
• The Water Gauge - medium - Elevation bars trap water between peaks - count the volume.
• The Window Cleaner - medium - Keep it fresh, keep it unique.
• The Word Census - easy - Who said what - and how many times?
• The Word Counter - easy - How many times does each word show up in a file?
• The Word Families - medium - Different spellings, same letters - they belong together.
• The Word Flipper - easy - The sentence stays, the words surrender.
• The Word Inventory - easy - Every word, twice over.
• The Word Map - easy - Input text. Output: word frequency.
• The Word Mismatch - easy - Some text does not match.
• The Yahtzee Engine - hard - Five dice. Six faces. Score it.
• The Yahtzee Scorer - medium - Dice scoring. Multiple categories evaluated.
• The Zero Propagator - medium - One zero can change the whole picture.
• The Zigzag Encoder - medium - The message snakes its way across the rails.
• Three project teams each know different languages - medium
• Three teams have overlapping skills - medium
• Threshold Filter - medium - Above the line or below it.
• Tokenize - easy - Split it apart. Keep the pieces.
• Top N Keys - medium - Most of them do not matter. The few that do stand out.
• Transform Column - easy - Same data, new shape.
• Translate this pseudocode to Python: start with a total of 0 - medium
• Transpose Table - medium - Rows become columns. Columns become rows.
• Triangle Validator - medium - Not every triangle is a triangle.
• Two boolean variables are given: `is_logged_in` and `has_permission` - medium
• Two configuration snapshots differ - medium
• Two employees have shift schedules - medium
• Two teams have different skills - medium
• Type Caster - easy - Wrong type. Fix it.
• Unbroken - easy - A single dip resets the clock. Find the longest the machine held over the line.
• Unflatten Keys - medium - Dots in the key names. Rebuild the structure.
• Unique Values - easy - Duplicates are noise. Remove them.
• Use a dict comprehension to invert country_codes (swap keys/values), keeping only countries with nam - medium
• Use a dictionary comprehension to create a dict that maps each integer from 1 to 5 to its cube (n ** - medium
• Use a dictionary comprehension to invert the colors dict by swapping each key with its value - medium
• Use a dictionary comprehension to map each word in the list ['hello', 'world', 'python'] to its leng - medium
• Use a dictionary comprehension with a condition to create a new dict containing only the scores that - medium
• Use a dictionary to count how many times each word appears in the list - medium
• Use a dict to classify HTTP status codes: map 200 to 'OK', 301 to 'Redirect', 404 to 'Not Found', 50 - medium
• Use a for loop over range(1, 6) to compute the sum of 1 through 5 inclusive - medium
• Use a for loop to iterate over range(1, 6) - medium
• Use a for loop with range to calculate the sum of numbers from 1 to 5 (inclusive) - medium
• Use a for loop with range() to print the numbers 1 through 5, each on its own line. - medium
• Use a for loop with .setdefault() to group the words list by each word's first letter - medium
• Use a list as a stack - medium
• Use a list comprehension to create a list of squares for numbers 1 through 6 - medium
• Use a list comprehension to create a list of squares of the even numbers from 0 to 9 (inclusive) - medium
• Use a list comprehension to filter instead of modifying during iteration - medium
• Use a list comprehension with a filter to create a list containing only the squares of odd numbers f - medium
• Use a list comprehension with a filter to keep only the words from the list that have more than 4 ch - medium
• Use 'and' as a guard: 'data and data.upper()' safely skips .upper() when data is None - medium
• Use any() to check if any number in [2, 4, 6, 7, 8] is odd - medium
• Use any() to check if any string starts uppercase, and all() to check if all strings start uppercase - medium
• Use a prefix sum to find the sum of the entire array [10, 20, 30, 40, 50] without re-summing - medium
• Use a set called seen and a list called unique to deduplicate ids while preserving order - medium
• Use a set comprehension to create a set of squares for numbers 1 through 5: {x**2 for x in range(1, - medium
• Use a set comprehension to extract all unique department names from the employee list - medium
• Use a set comprehension with a filter to extract unique even numbers from the list [1, 2, 2, 3, 4, 4 - medium
• Use a set to efficiently deduplicate a list while preserving order - medium
• Use a single chained comparison (x < y < z) to check whether three numbers are in strictly ascending - medium
• Use a sliding window of size 3 to compute moving averages of [10, 20, 30, 40, 50] - medium
• Use a ternary expression to compute abs_n: n if non-negative, else -n. - medium
• Use a ternary to assign label: str(count) + ' items' if count != 1, else str(count) + ' item'. - medium
• Use a while loop to count down from 3 to 1, printing each number - medium
• Use bisect.insort to build a sorted list from the unsorted values [5, 2, 8, 1, 9, 3] - medium
• Use chained bracket access to print the "port" value from inside the "database" nested dictionary. - medium
• Use chained .get() calls to safely extract the city from nested dicts - medium
• Use .copy() to create a copy of original - medium
• Use Counter from the collections module to count the frequency of each word in the list words - medium
• Use Counter to count the characters in 'mississippi' - medium
• Use Counter to count the letters in 'abracadabra' - medium
• Use Counter to find the most common character in 'abracadabra' - medium
• Use defaultdict(int) to count how many times each character appears in the string 'banana' - medium
• Use defaultdict(list) to group the records list by department - medium
• Use defaultdict(list) to group these (category, item) pairs: ('fruit', 'apple'), ('veg', 'carrot'), - medium
• Use defaultdict(list) to group these pairs by the first element: ('a', 1), ('b', 2), ('a', 3), ('b', - medium
• Use defaultdict(set) to track unique visitors per page: ('home', 'alice'), ('about', 'bob'), ('home' - medium
• Use De Morgan's Laws to simplify: not (x > 5 and x < 10) is equivalent to (x <= 5 or x >= 10) - medium
• Use dict() and zip() together to create a dictionary from the keys and values lists - medium
• Use divmod(17, 5) to get the quotient and remainder - medium
• Use enumerate() to loop over the list fruits - medium
• Use enumerate with reversed to print items from ['a', 'b', 'c', 'd'] in reverse with their original - medium
• Use filter() with a lambda for even numbers, then map() with a lambda to square them - medium
• Use filter() with a lambda to keep only positive numbers from [-3, -1, 0, 2, 5, -4, 7] - medium
• Use filter() with a lambda to keep only the even numbers from [1, 2, 3, 4, 5, 6, 7, 8] - medium
• Use filter() with a lambda to keep only the even numbers from the list - medium
• Use .find() to search for 'dog' in the sentence and print the result (returns -1 when not found). - medium
• Use frozensets as dictionary keys - medium
• Use functools.reduce to compute the product of all numbers in [1, 2, 3, 4, 5] - medium
• Use guard clauses with continue to skip records where value is None or negative - medium
• Use heapq.nsmallest and heapq.nlargest to find the 3 smallest and 3 largest values from [15, 3, 28, - medium
• Use 'is not None' to correctly detect that result=0 is a found value (not falsy-failed) - medium
• Use @lru_cache(maxsize=128) to memoize a recursive factorial function - medium
• Use map() to convert the list of string prices to integers, then print their sum. - medium
• Use map() with a lambda to double each number in [1, 2, 3, 4, 5], then use filter() with a lambda to - medium
• Use map() with a lambda to extract just the "name" value from each dictionary in the users list - medium
• Use multiple assignment to set x to 10 and y to 20 on one line - medium
• Use multiple assignment to set x to 5 and y to 10 in a single line - medium
• Use nested if statements to check account access - medium
• Use .pop() to remove and capture the last item from the pipeline list. - medium
• Use range() with a step argument to print all even numbers from 2 to 10 (inclusive), each on its own - medium
• Use selective unpacking with _ placeholders to extract only the grade and major (3rd and 4th values) - medium
• Use set operators to find the intersection (&), union (|), and difference (-) of team_a and team_b - medium
• Use short-circuit evaluation: given x = 5, print the results of (x > 3 or x > 10), (x > 3 and x < 10 - medium
• Use sorted() with a lambda function to sort the list [-3, 1, -2, 4] by absolute value (smallest to l - medium
• Use sorted() with a lambda key to sort the list of tuples [('Charlie', 25), ('Alice', 30), ('Bob', 2 - medium
• Use sys.getsizeof to compare memory usage of a 5-element list [0,1,2,3,4] vs a 5-element dict {0:0,1 - medium
• Use the accumulator pattern: count how many words in the list have more than 4 characters - medium
• Use the filter pattern: create an empty list called big, then loop through values - medium
• Use the modulo operator (%) to check if `number` is even or odd - medium
• Use the &= operator to keep only items present in the intersection set. - medium
• Use the | operator to merge defaults and user_prefs into a NEW dictionary called combined, without m - medium
• Use the * operator to repeat the string "ab" exactly 4 times and print the result. - medium
• Use the 'or' operator to provide default values - medium
• Use the transform pattern to convert each Celsius temperature to Fahrenheit using the formula F = C - medium
• Use the two-pass pattern: first calculate the average of the scores, then build a list of scores tha - medium
• Use the two-pointer technique on a sorted list [1, 3, 5, 7, 9, 11] to find if any two numbers sum to - medium
• Use the walrus operator in a list comprehension: compute x * 3 once with := and filter where the res - medium
• Use the walrus operator in a list comprehension: create squares where (sq := n**2) > 10 - medium
• Use .update() to merge extras into profile - medium
• Use zip() to combine items, prices, and quantities together - medium
• Using collections.deque with maxlen=3, push 1, 2, 3, 4, 5 in order using append - medium
• Using dataclasses.dataclass with frozen=True, define class Point with fields x: int and y: int - medium
• Using functools.lru_cache(maxsize=None), define fib(n) recursively where fib(0) = 0, fib(1) = 1, els - medium
• Validate a data record: check that `name` is not empty AND `age` is between 0 and 150 (inclusive) - medium
• Validate Email - medium - Looks like an email. But is it?
• Value Count - easy - How many of each? Count them.
• Variables first and last hold name parts - medium
• Variables item, price, and qty are provided - medium
• Word Counter - easy - Words in, counts out.
• Write a comment that says "Calculate the area" on its own line, then create a variable called area s - medium
• Write a decorator called 'announce' that prints 'Calling function!' before the decorated function ru - medium
• Write a decorator called call_counter that counts how many times a function is called - medium
• Write a decorator called 'double_result' that doubles the return value of any function it wraps - medium
• Write a function called count_target(items, target) that counts how many times target appears in ite - medium
• Write a function called has_duplicates that takes a list and returns True if it contains duplicate v - medium
• Write a function called make_multiplier(n) that returns a lambda which multiplies its argument by n - medium
• Write a function called min_max that takes a list and returns a tuple of (minimum, maximum) using mi - medium
• Write a function called safe_average(numbers) that returns the average of a list - medium
• Write a function is_balanced(s) that uses a stack to check if parentheses are balanced - medium
• Write a function is_palindrome(s) using two pointers (left and right) that checks if a string reads - medium
• Write a function is_palindrome(s) using two pointers that checks if a string reads the same forwards - medium
• Write a function safe_max(numbers) that returns the largest number in a list, or None if the list is - medium
• Write a function that checks if two strings are anagrams using Counter - medium
• Write a function two_sum(nums, target) using a hash map - medium
• Write a function two_sum_sorted(nums, target) using two pointers on a sorted list - medium
• Write a generator function called 'evens' that yields even numbers from 2 to 10 (inclusive) - medium
• Write a generator function called 'powers_of_two' that yields 2**0, 2**1, 2**2, 2**3, and 2**4 in or - medium
• Write an if-elif-else chain to assign a letter grade based on `score`: "A" if score >= 90, "B" if sc - medium
• Write an if-else statement that prints "approved" if `balance` is greater than or equal to 100, othe - medium
• Write a recursive function factorial(n) that returns n - medium
• Write a recursive function sum_list(lst) that returns the sum of all elements - medium
• Write a simple decorator called shout that converts a function's string return value to uppercase - medium
• You have a list of weekly metrics - medium
• You have three fruit variables - medium
• You have two variables: a = 100 and b = 200 - medium
• Zip to Record - easy - Two lists become one record.