Overlap two intervals
Given two closed intervals, return their overlap as a tuple or None if they do not overlap.
Find all indexes of a substring
Write a function that returns a list of all starting indexes where a substring appears in a string, including overlapping occurrences.
Count Substrings
Implement a function that counts non-overlapping occurrences of a substring in a given string.
Merge intervals
Merge all overlapping intervals and return a sorted result.
Merge time intervals
Given a list of time intervals, merge all overlapping intervals and return the merged intervals.
Pairwise Sequence Pairs
Write a generator function pairwise that yields each consecutive overlapping pair from any iterable as lists.
Minimum Number of Arrows to Burst Balloons
Given balloon intervals, find the minimum number of arrows to burst all balloons by merging overlaps.
Non-overlapping Intervals
Given a list of intervals, return the minimum number of intervals to remove to make the rest non-overlapping.
Max events attended
Given a list of events with start and end times, find the maximum number of non-overlapping events you can attend.
Schedule conflict check
Write a function that takes a list of time intervals and returns True if any two overlap.
Showing 10 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.