Garbage Collection Hint
Write a function that predicts when an object is garbage collected based on reference counting.
Merge dicts summing values
Write a function that merges two dictionaries by summing values for duplicated keys.
Nested get with dotted path
Implement a function that safely retrieves a value from a deeply nested dictionary using a dot-separated path, returning a default if any key is missing.
Anagram Dictionary Groups Lite
Group a list of words into anagrams using a dictionary keyed by sorted characters.
Replace keys with a mapping
Write a function that renames keys in a dictionary according to a mapping, with duplicate handling.
Anagram Groups by Size
Group a list of words into anagram groups and return them sorted by group size and lexicographically.
Group by Department
Implement a function that groups a list of employee dictionaries by department, returning a dictionary keyed by department with lists of employee dictionaries.
Pivot sales by product
Write a function that pivots sales records into a dictionary keyed by product with monthly totals.
Serialize dict to TOML-like
Convert nested Python dicts into a simplified TOML-like string with sorted keys, type-aware formatting, and flat table sections.
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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.