LRU cache decorator
Implement @lru_cache(maxsize=N) for unary functions using OrderedDict.
Longest increasing subsequence
Return the length of the longest strictly increasing subsequence.
Topological sort (Kahn)
Return a valid topological ordering of tasks, or [] if a cycle exists.
Word ladder length
Return the length of the shortest transformation from beginWord to endWord changing one letter at a time.
Showing 4 challenges · hard · Data Structures & Algorithms
Data Structures & Algorithms — Python coding challenges
What you will find here
This page lists data structures & algorithms challenges — real Python problems you solve in the browser IDE with instant test feedback. Each challenge includes a clear brief, starter code, and automated checks.
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.