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.
Prepend a new head
Insert value at the front of the list.
Append a new tail
Add value after the last node.
Palindrome linked values
Check whether values read the same forwards and backwards.
Rotate list left by k
Move the first k nodes to the end (k may exceed length; use modulo).
Merge two sorted lists
Merge two ascending integer lists into one sorted list.
Remove duplicate values
Keep first occurrence of each value while preserving order.
Pairwise sum of adjacent nodes
Sum each adjacent pair; keep a lone last node as-is.
Count nodes equal to target
Count how many times target appears in the list.
Zip two linked lists
Interleave values from a and b until both are exhausted.
Split list at index
Return prefix and suffix tuples at index k.
Second node value
Return the second value or None if fewer than two nodes.
Drop the tail node
Return a new list without the last node.
Join node values with arrows
Format string node values as 'a -> b -> c'; empty list returns ''.
Insert value at index
Insert x at index i in a new list.
Compare two linked lists
Return True when both lists have identical values in order.
Spiral Matrix Order
Given a 2D matrix, return all elements in clockwise spiral order starting from the top-left.
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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.