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Practice › LeetCode › LeetCode 38xx ›

LeetCode 3829 - Design Ride Sharing System

LeetCode Problem 3829 Difficulty: 🟡 Medium Topics: Hash Table, Design, Queue, Data Stream Solution Problem Understanding The problem asks us to design a ride sharing system that manages both riders and drivers as they enter the system, and to match them in a first-come, first-served order. The system must track riders who are waiting for rides, drivers who are available, and support canceling rider requests. Inputs include rider and driver...

Practice › LeetCode › LeetCode 21xx ›

LeetCode 2102 - Sequentially Ordinal Rank Tracker

LeetCode Problem 2102 Difficulty: 🔴 Hard Topics: Design, Heap (Priority Queue), Data Stream, Ordered Set Solution Problem Understanding The problem asks us to design a data structure that continuously tracks scenic locations ranked by two rules: A higher score means a better location. If two locations have the same score, the lexicographically smaller name is considered better. The system supports two operations: add(name, score) inserts a new location. get() returns...

Practice › LeetCode › LeetCode 33xx ›

LeetCode 3369 - Design an Array Statistics Tracker

LeetCode Problem 3369 Difficulty: 🔴 Hard Topics: Hash Table, Binary Search, Design, Queue, Heap (Priority Queue), Data Stream, Ordered Set Solution Problem Understanding The problem asks us to design a data structure that supports a stream of operations on a dynamic collection of integers. Numbers are added over time, and the oldest inserted number can also be removed. At any point, we must efficiently answer three statistical queries: The floored...

Practice › LeetCode › LeetCode 25xx ›

LeetCode 2526 - Find Consecutive Integers from a Data Stream

LeetCode Problem 2526 Difficulty: 🟡 Medium Topics: Hash Table, Design, Queue, Counting, Data Stream Solution Problem Understanding The problem asks us to design a data structure that continuously processes a stream of integers and determines whether the most recent k integers are all equal to a specific target value. We are given two parameters when initializing the data structure: value , which represents the integer we are interested in tracking....

Practice › LeetCode › LeetCode 01xx ›

LeetCode 170 - Two Sum III - Data structure design

LeetCode Problem 170 Difficulty: 🟢 Easy Topics: Array, Hash Table, Two Pointers, Design, Data Stream Solution Problem Understanding The problem asks us to design a data structure that supports two operations efficiently over a stream of integers. The first operation, add(number) , inserts a number into the data structure. Numbers may appear multiple times, so duplicates must be handled correctly. The second operation, find(value) , checks whether there exists any...

Practice › LeetCode › LeetCode 06xx ›

LeetCode 642 - Design Search Autocomplete System

LeetCode Problem 642 Difficulty: 🔴 Hard Topics: String, Depth-First Search, Design, Trie, Sorting, Heap (Priority Queue), Data Stream Solution Problem Understanding The problem asks us to design an autocomplete system that behaves similarly to a search engine suggestion feature. The system starts with a collection of historical sentences and the number of times each sentence has been typed before. As the user types characters one by one, the system must...

Practice › LeetCode › LeetCode 18xx ›

LeetCode 1825 - Finding MK Average

LeetCode Problem 1825 Difficulty: 🔴 Hard Topics: Design, Queue, Heap (Priority Queue), Data Stream, Ordered Set Solution Problem Understanding The problem asks us to design a data structure that continuously receives numbers from a stream and can efficiently compute a special average called the MKAverage. For every query, we only care about the most recent m elements in the stream. From those m elements: Remove the smallest k numbers. Remove...

Practice › LeetCode › LeetCode 16xx ›

LeetCode 1670 - Design Front Middle Back Queue

LeetCode Problem 1670 Difficulty: 🟡 Medium Topics: Array, Linked List, Design, Queue, Doubly-Linked List, Data Stream Solution Problem Understanding The problem is asking us to design a specialized queue that allows insertions and removals not only at the front and back, but also at the middle of the queue. We need to maintain the queue such that we can efficiently access and modify elements at these three positions. The middle...

Practice › LeetCode › LeetCode 16xx ›

LeetCode 1656 - Design an Ordered Stream

LeetCode Problem 1656 Difficulty: 🟢 Easy Topics: Array, Hash Table, Design, Data Stream Solution Problem Understanding This problem asks us to simulate a data stream where each element arrives with a unique ID in arbitrary order. Each element consists of an integer idKey (between 1 and n ) and a string value . The goal is to design a stream that, after every insertion, returns the largest contiguous chunk of...

Practice › LeetCode › LeetCode 10xx ›

LeetCode 1032 - Stream of Characters

LeetCode Problem 1032 Difficulty: 🔴 Hard Topics: Array, String, Design, Trie, Data Stream Solution Problem Understanding The problem asks us to design a data structure that processes a stream of characters one at a time. After each newly added character, we must determine whether any suffix of the stream matches one of the words from a predefined dictionary. A suffix means the ending portion of the stream. For example, if...

Practice › LeetCode › LeetCode 09xx ›

LeetCode 901 - Online Stock Span

LeetCode Problem 901 Difficulty: 🟡 Medium Topics: Stack, Design, Monotonic Stack, Data Stream Solution Problem Understanding The problem asks us to design a class that processes stock prices one day at a time and, for every new price, returns the stock span for that day. The stock span is defined as the number of consecutive days ending today where the stock price was less than or equal to today's price....

Practice › LeetCode › LeetCode 09xx ›

LeetCode 933 - Number of Recent Calls

LeetCode Problem 933 Difficulty: 🟢 Easy Topics: Design, Queue, Data Stream Solution Problem Understanding The problem asks us to implement a class RecentCounter that tracks the number of requests (or pings) made in the last 3000 milliseconds. Every time the ping(t) method is called with a time t , we are asked to return how many requests occurred within the time interval [t - 3000, t] . The class starts...

Practice › LeetCode › LeetCode 14xx ›

LeetCode 1429 - First Unique Number

LeetCode Problem 1429 Difficulty: 🟡 Medium Topics: Array, Hash Table, Design, Queue, Data Stream Solution Problem Understanding The problem requires designing a data structure that can efficiently maintain and retrieve the first unique integer in a queue of numbers. You are given an initial list of integers, and after that, the data structure should support two operations efficiently: retrieving the first unique number ( showFirstUnique ) and adding a new...

Practice › LeetCode › LeetCode 07xx ›

LeetCode 703 - Kth Largest Element in a Stream

LeetCode Problem 703 Difficulty: 🟢 Easy Topics: Tree, Design, Binary Search Tree, Heap (Priority Queue), Binary Tree, Data Stream Solution Problem Understanding The problem asks us to design a data structure that continuously tracks the kth largest element in a stream of integers. We are given an integer k and an initial list of numbers called nums . After initialization, new numbers are added one at a time using the...

Practice › LeetCode › LeetCode 14xx ›

LeetCode 1472 - Design Browser History

LeetCode Problem 1472 Difficulty: 🟡 Medium Topics: Array, Linked List, Stack, Design, Doubly-Linked List, Data Stream Solution Problem Understanding The problem is asking us to simulate a single-tab browser with a history mechanism. You start on a homepage , and from there, you can visit new URLs, back track a certain number of steps, or forward a certain number of steps. The inputs consist of method calls: BrowserHistory(homepage) initializes the...

Practice › LeetCode › LeetCode 20xx ›

LeetCode 2013 - Detect Squares

LeetCode Problem 2013 Difficulty: 🟡 Medium Topics: Array, Hash Table, Design, Counting, Data Stream Solution Problem Understanding The problem presents a stream of points in a 2D plane and asks us to design a data structure that supports two operations efficiently: adding points and counting squares. The add operation inserts a point into the data structure, and the count operation calculates the number of axis-aligned squares that can be formed...

Practice › LeetCode › LeetCode 02xx ›

LeetCode 295 - Find Median from Data Stream

LeetCode Problem 295 Difficulty: 🔴 Hard Topics: Two Pointers, Design, Sorting, Heap (Priority Queue), Data Stream Solution Problem Understanding The problem asks us to design a data structure that continuously receives integers from a stream and can efficiently return the median of all numbers seen so far. The median is defined as the middle element in a sorted list. If the number of elements is odd, the median is the...

Practice › LeetCode › LeetCode 03xx ›

LeetCode 352 - Data Stream as Disjoint Intervals

LeetCode Problem 352 Difficulty: 🔴 Hard Topics: Hash Table, Binary Search, Union-Find, Design, Data Stream, Ordered Set Solution LeetCode 352 - Data Stream as Disjoint Intervals Problem Understanding This problem asks us to process a stream of non-negative integers and continuously maintain a compact representation of all numbers seen so far. Instead of storing every individual number separately, we want to group consecutive numbers into disjoint intervals. An interval [start,...

Practice › LeetCode › LeetCode 13xx ›

LeetCode 1352 - Product of the Last K Numbers

LeetCode Problem 1352 Difficulty: 🟡 Medium Topics: Array, Math, Design, Data Stream, Prefix Sum Solution Problem Understanding This problem asks us to design a data structure that continuously processes a stream of integers and supports querying the product of the last k inserted numbers. The ProductOfNumbers class starts with an empty sequence. Every time add(num) is called, a new integer is appended to the stream. Later, getProduct(k) must return the...

Practice › LeetCode › LeetCode 03xx ›

LeetCode 346 - Moving Average from Data Stream

LeetCode Problem 346 Difficulty: 🟢 Easy Topics: Array, Design, Queue, Data Stream Solution Problem Understanding The problem asks us to design a data structure that continuously receives integers from a stream and returns the average of the most recent values within a fixed-size sliding window. A sliding window means that we only care about the latest size elements. As new values arrive, older values eventually fall out of the window...

Practice › LeetCode › LeetCode 15xx ›

LeetCode 1500 - Design a File Sharing System

LeetCode Problem 1500 Difficulty: 🟡 Medium Topics: Hash Table, Design, Sorting, Heap (Priority Queue), Data Stream Solution Problem Understanding This problem asks us to design a miniature peer-to-peer file sharing system. The file is divided into m chunks, where every chunk has an ID from 1 to m . Users can join the system while already owning some chunks, leave the system entirely, and request chunks from other users. The...

Practice › LeetCode › LeetCode 03xx ›

LeetCode 362 - Design Hit Counter

LeetCode Problem 362 Difficulty: 🟡 Medium Topics: Array, Binary Search, Design, Queue, Data Stream Solution Problem Understanding The problem asks us to design a data structure that tracks how many events, called "hits", occurred during the last 5 minutes. Every hit comes with a timestamp measured in seconds, and timestamps are guaranteed to arrive in chronological order. The class must support three operations: hit(timestamp) records a new hit at the...

Practice › LeetCode › LeetCode 03xx ›

LeetCode 359 - Logger Rate Limiter

LeetCode Problem 359 Difficulty: 🟢 Easy Topics: Hash Table, Design, Data Stream Solution Problem Understanding The problem asks us to design a logging system that controls how frequently identical messages can be printed. Each message is associated with a timestamp, and the same message is only allowed to be printed once every 10 seconds. More specifically, when a message is printed at timestamp t , the next time the exact...

Practice › LeetCode › LeetCode 20xx ›

LeetCode 2034 - Stock Price Fluctuation

LeetCode Problem 2034 Difficulty: 🟡 Medium Topics: Hash Table, Design, Heap (Priority Queue), Data Stream, Ordered Set Solution Here’s a complete, detailed technical solution guide for LeetCode 2034 - Stock Price Fluctuation following your formatting and content requirements. Problem Understanding The problem presents a stream of stock price records where each record consists of a timestamp and a price . However, the stream is not guaranteed to be chronological, and...

Practice › LeetCode › LeetCode (archived) › LeetCode 09xx ›

LeetCode 933: Number of Recent Calls

Problem Restatement We need to implement a class called RecentCounter . It supports one main operation: ping(t) Each call records a request at time t , measured in milliseconds. After recording the request, ping(t) must return how many requests happened in the time range: [t - 3000, t] The current request is included. The problem guarantees that every new t is strictly larger than the previous one. The official statement...

Practice › LeetCode › LeetCode (archived) › LeetCode 07xx ›

LeetCode 703: Kth Largest Element in a Stream

Problem Restatement We need to design a class called KthLargest . The class receives: k nums nums is the initial stream of integers. After that, the class supports an operation: add(val) This adds val to the stream and returns the kth largest element among all numbers seen so far. The kth largest element means the element at position k if all numbers are sorted from largest to smallest. Duplicates count...

Practice › LeetCode › LeetCode (archived) › LeetCode 09xx ›

LeetCode 901: Online Stock Span

Problem Restatement We need to design a class called StockSpanner . The class receives stock prices one day at a time through the method next(price) . For each new price, we return its stock span. The span is the number of consecutive days ending today where each price was less than or equal to today's price. For example: prices = [100, 80, 60, 70, 60, 75, 85] The spans are:...

Practice › LeetCode › LeetCode (archived) › LeetCode 02xx ›

LeetCode 295: Find Median from Data Stream

Problem Restatement We need to design a class called MedianFinder . It supports two operations: addNum(num) findMedian() addNum(num) adds one integer from the data stream. findMedian() returns the median of all numbers added so far. The median is the middle value in a sorted list. If the list has an even number of values, the median is the average of the two middle values. The answer is accepted if it...

Practice › LeetCode › LeetCode (archived) › LeetCode 03xx ›

LeetCode 362: Design Hit Counter

Problem Restatement We need to design a hit counter. The counter supports two operations: Method Meaning hit(timestamp) Record one hit at timestamp getHits(timestamp) Return how many hits happened in the past 300 seconds The timestamp is given in seconds. Calls arrive in chronological order, so timestamps are monotonically increasing. Multiple hits may happen at the same timestamp. The time window is the past 5 minutes, which means the past 300...

Practice › LeetCode › LeetCode (archived) › LeetCode 03xx ›

LeetCode 359: Logger Rate Limiter

Problem Restatement We need to design a logger system. The logger receives messages with timestamps. Each message should be printed only if the same message was not printed in the last 10 seconds. Given: timestamp: int message: str Return: True if the message should be printed. Return: False if the message should be blocked. A message printed at timestamp t prevents the same message from being printed again until timestamp...

Practice › LeetCode › LeetCode (archived) › LeetCode 03xx ›

LeetCode 352: Data Stream as Disjoint Intervals

Problem Restatement We need to design a data structure called SummaryRanges . It receives non-negative integers from a data stream, one number at a time. After each insertion, it should be able to return all numbers seen so far as a sorted list of disjoint intervals. For example, if the stream gives: 1, 3, 7, 2, 6 Then the intervals change like this: after 1: [[1, 1]] after 3: [[1,...

#data-stream

LeetCode 3829 - Design Ride Sharing System

LeetCode 2102 - Sequentially Ordinal Rank Tracker

LeetCode 3369 - Design an Array Statistics Tracker

LeetCode 2526 - Find Consecutive Integers from a Data Stream

LeetCode 170 - Two Sum III - Data structure design

LeetCode 642 - Design Search Autocomplete System

LeetCode 1825 - Finding MK Average

LeetCode 1670 - Design Front Middle Back Queue

LeetCode 1656 - Design an Ordered Stream

LeetCode 1032 - Stream of Characters

LeetCode 901 - Online Stock Span

LeetCode 933 - Number of Recent Calls

LeetCode 1429 - First Unique Number

LeetCode 703 - Kth Largest Element in a Stream

LeetCode 1472 - Design Browser History

LeetCode 2013 - Detect Squares

LeetCode 295 - Find Median from Data Stream

LeetCode 352 - Data Stream as Disjoint Intervals

LeetCode 1352 - Product of the Last K Numbers

LeetCode 346 - Moving Average from Data Stream

LeetCode 1500 - Design a File Sharing System

LeetCode 362 - Design Hit Counter

LeetCode 359 - Logger Rate Limiter

LeetCode 2034 - Stock Price Fluctuation

LeetCode 933: Number of Recent Calls

LeetCode 703: Kth Largest Element in a Stream

LeetCode 901: Online Stock Span

LeetCode 295: Find Median from Data Stream

LeetCode 362: Design Hit Counter

LeetCode 359: Logger Rate Limiter

LeetCode 352: Data Stream as Disjoint Intervals