Python coding challenges: "recursion"

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Recursion & Backtracking medium

Beautiful Arrangement Count

Count the number of permutations of 1..n such that for every index i, either i is divisible by the number at that position or the number is divisible by i.

recursion backtracking permutations

+30 pts 30m

Recursion & Backtracking medium

Rat in a Maze

Count the number of distinct paths a rat can take from top-left to bottom-right in a binary grid, moving down or right and avoiding walls.

backtracking recursion maze

+25 pts 30m

Stacks & Queues medium

Decode Nested String

Implement a function that decodes a string with nested encoding patterns.

stack string parsing

+25 pts 30m

Data Formats & Parsing medium

Flatten nested JSON

Write a function that flattens nested JSON objects into a flat dictionary with dot-separated keys, handling lists and empty objects.

json recursion dictionaries

+20 pts 25m

Showing 25–28 of 28 challenges · medium

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.

Python Coding Challenges