Dot Product of Vectors
Implement a function that returns the dot product of two numeric vectors.
Triangle Minimum Path
Compute the minimum path sum from top to bottom of a triangle given as a list of lists.
Count nodes in a linked list
Return how many values appear in the list (one per node).
Read the head node value
Return the first value or None when the list is empty.
Read the tail node value
Return the last value or None when the list is empty.
Reverse a linked list copy
Return a new list with node values in reverse order without mutating the input.
Concatenate two linked lists
Append the second list's nodes after the first and return a new list.
Value at index n
Return the value at zero-based index n or None if out of range.
Middle node index
Return the floor middle index for a non-empty list.
Sum all node values
Add every integer payload in the list.
Maximum node value
Return the largest integer or None when empty.
Remove the head node
Return a new list without the first node.
Matrix Multiply 2D
Write a function that multiplies two 2D matrices (lists of lists) and returns the product matrix.
Transpose 2D Array
Implement a function that returns the transpose of a rectangular 2D list.
Inner Join Two Tables
Write a function that inner joins two lists of dictionaries on a common key and returns the combined rows.
Select All Users
Write a function that connects to an in-memory SQLite database and returns all users as a list of lists.
Element-wise vector addition
Add equal-length numeric lists element-wise.
Showing 73–89 of 89 challenges · easy
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.