Parse key-value lines
Parse structured key-value lines into a dictionary with support for quoted values and escaped characters.
Word Break DP
Implement a function to check if a string can be segmented into space-separated dictionary words.
Vertical Order Traversal
Compute the vertical order traversal of a binary tree, grouping nodes by column and row.
Alien Dictionary Order
Given a sorted list of words in an alien language, derive the order of its unique letters.
Flatten nested JSON
Write a function that flattens nested JSON objects into a flat dictionary with dot-separated keys, handling lists and empty objects.
Unflatten JSON dict
Given a flat dictionary with keys like 'a.b.c', reconstruct the nested dictionary where each dotted segment becomes a nested level.
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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.