Flatten nested list
Yield every integer from an arbitrarily nested list, depth-first.
Infinite counter generator
Create an infinite counter starting from `start`, stepping by `step`.
Generator Pipeline
Implement a generator function that yields only even numbers from an input list, squared.
Range-like generator
Implement a custom generator that yields numbers like Python's range but with flexible bounds.
Fibonacci Generator
Create a generator function that yields Fibonacci numbers from 0 upward until a given limit.
Prime Sieve Generator
Implement a generator function that yields prime numbers from 2 up to a specified limit, using an efficient sieve approach.
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`.
Permutation Generator
Write a function that returns all permutations of a list of distinct integers.
Combination Generator
Write a recursive function that returns all combinations of length k from a list of distinct integers.
Showing 16 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.