Buildings with ocean view
Given building heights, return sorted indices of buildings that have a clear view of the ocean to their right.
Sum of Subarray Minimums
Given an integer array, sum the minimum of all contiguous subarrays modulo 10^9+7.
Asteroid Collision
Simulate asteroid collisions with a stack and return the remaining asteroids in original order.
Find K pairs with smallest sums
Given two sorted arrays and an integer k, return the k smallest pairs (u, v) with the smallest sums, sorted by sum.
Flatten matrix to vector
Read rows left-to-right, top-to-bottom.
Square each element
Return element-wise squares.
Absolute value per element
Return element-wise absolute values.
Keep positive elements
Return values strictly greater than zero.
Prefix sum vector
Return running totals for each prefix of the vector.
Element-wise multiply
Multiply corresponding elements.
Count non-zero entries
Count elements not equal to zero.
Reverse vector order
Return elements in opposite order.
Transpose a matrix
Swap rows and columns for a rectangular matrix.
L2 norm of vector
Return Euclidean length.
Showing 49–62 of 62 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.