Practical Data Structures in Python

This repo is a collection of small data structure examples I made while practicing core CS topics.

I wanted the examples to feel more useful than just textbook code, so each one is connected to a normal software problem.

What's Inside

File	Data Structure	Example Use
lru_cache.py	dictionary + doubly linked list	keeping recently used values
dependency_resolver.py	graph	ordering tasks with prerequisites
autocomplete.py	trie	finding words from a prefix
priority_task_queue.py	heap	picking the most important task first
union_find.py	disjoint set	checking which items are connected

Why I Made This

I wanted a GitHub project that shows I understand data structures, but in a way that is still practical.

For example:

• caches need fast lookup
• autocomplete needs prefix search
• task queues need priorities
• dependency planners need graph traversal
• connected groups can be handled with union-find

Quick Start

Run the tests:

PYTHONPATH=src python -m unittest discover -s tests

Run the demo:

PYTHONPATH=src python examples/demo.py

Example

from practical_ds.lru_cache import LRUCache

cache = LRUCache(capacity=2)
cache.put("user:1", "Saina")
cache.put("user:2", "Ari")
cache.get("user:1")
cache.put("user:3", "Mina")

assert cache.get("user:2") is None

Here, user:2 gets removed because it was the least recently used item.

What I Practiced

• writing clean Python classes
• using tests to check behavior
• thinking about time complexity
• connecting data structures to real examples
• making a repo that is easy to run