Window Iterator
Implement a generator that yields consecutive windows of a given size from any iterable.
Pairwise Sequence Pairs
Write a generator function pairwise that yields each consecutive overlapping pair from any iterable as lists.
Groupby Consecutive
Write a generator function that yields (value, list_of_occurrences) for each run of consecutive equal items.
Collatz Generator
Implement a generator function that yields the Collatz sequence starting from a given positive integer.
Digit Expansion Generator
Create a generator that lazily yields each decimal digit of a non-negative integer from most significant to least significant.
File Line Reader Generator
Implement a generator function that reads a file-like object and yields each non-empty line without loading the whole file into memory.
Tree inorder generator
Write a generator function that yields a binary tree's node values in inorder traversal.
Yield from delegation
Implement a generator that flattens nested iterables of any depth using `yield from`.
Flatten Nested List Iterator
Implement a class that iterates over all integers in a nested list structure in depth-first order.
Iterator protocol class
Implement a class that follows the iterator protocol and yields squared numbers up to a given limit.
Cartesian Product Generator
Implement a generator function that yields the Cartesian product of multiple input iterables without precomputing all results.
Batch Iterator
Implement a generator that yields batches of a given size from any iterable, including the final partial batch.
Zip Longest Fill
Create an iterator that yields lists from multiple iterables, padding with a fill value when lengths differ.
Graph DFS Generator
Implement a generator function that performs a depth-first traversal of a graph without recursion.
Close generator early
Wrap any iterable in a generator that tracks yielded items and supports close() correctly.
Once Decorator: Run a Function Only Once
Implement a decorator that caches and returns the result of the first call for subsequent calls.
Timing Decorator
Implement a decorator that prints the execution time of a function.
Memoize with TTL
Implement a decorator that caches function results for a limited time, returning cached values within the TTL and recomputing after expiry.
LRU Memoize
Implement an LRU memoization decorator that caches results for a fixed number of arguments.
Context Manager Class
Implement a context manager class that measures execution time and sets duration, with None if an exception occurred.
Cached Property Manual
Implement a decorator that turns a method into a lazy cached attribute per instance.
Rate Limit Decorator
Implement a decorator that enforces a maximum number of calls per second for any function.
Cache result decorator
Create a decorator that stores results of function calls keyed by positional arguments.
Profile time decorator
Create a decorator that tracks how many times a function is called and its cumulative execution time.
Showing 433–456 of 925 challenges
Guide: free Python coding challenges
Practice Python by solving problems
PythonSkillset challenges are hands-on coding exercises from beginner to advanced. Open a challenge, read the problem, write Python in the split-pane editor, and run tests with Pyodide — no install required.
How to use the arena
- Pick a category — basics, algorithms, strings, and more
- Open a challenge, read the statement, and edit the starter code
- Run tests, fix failures, then try a related quiz or tutorial lesson
Challenges vs tutorials and quizzes
Challenges test what you can build under constraints. For guided teaching, use our Python tutorials. For quick checks, try quizzes or copy snippets from code samples.