Practice Arena

Python Coding Challenges

Write real Python in the browser. Instant feedback. From beginner to expert.

925 challenges 556 easy 323 medium 46 hard
All Easy Medium Hard
All Python Basics Strings & Text Lists & Arrays Dicts & Sets Functions & Closures OOP & Classes Data Structures & Algorithms Advanced Python Iterators & Generators Decorators & Context Managers Error Handling & Exceptions Regular Expressions Math & Number Theory Bit Manipulation Dynamic Programming Trees & Binary Trees Graphs & Graph Algorithms Recursion & Backtracking Greedy Algorithms Binary Search Two Pointers & Sliding Window Stacks & Queues Heaps & Priority Queues Linked Lists Matrix & 2D Arrays Datetime & Time Calculations Data Formats & Parsing SQL & SQLite Numpy & Vectorized Computing Cryptography & Hashing
Strings & Text hard

Basic Calculator III

Implement a recursive descent parser to evaluate a fully parenthesized arithmetic expression with +, -, *, / and parentheses.

parsing string expression
+45 pts 40m
Advanced Python hard

Data pipeline

Implement a Pipeline class supporting pipe chaining with the | operator.

functional OOP pipeline
1
+40 pts 35m
Dynamic Programming hard

Cherry Pickup Maximum

Given a grid with cherries, find the maximum cherries you can collect using two paths from top-left to bottom-right.

dynamic-programming 2d-grid grid-walk
+40 pts 35m
Graphs & Graph Algorithms hard

Swim in Rising Water

Find the minimum time needed to swim from the top-left to the bottom-right of a grid where water level rises and you can only move to cells with elevation ≤ current time.

graph minimax priority-queue
+30 pts 20m
Recursion & Backtracking hard

Remove invalid parentheses

Given a string with parentheses and letters, return all valid strings after removing the minimum number of invalid parentheses.

backtracking parentheses string
+45 pts 40m
Greedy Algorithms hard

Remove K Digits to Form the Smallest Number

Given a non-negative integer as a string, remove exactly k digits to form the smallest possible integer without leading zeros.

greedy stack string
+45 pts 35m
Two Pointers & Sliding Window hard

Subarrays with K different ints

Count the number of contiguous subarrays that contain exactly K distinct integers.

sliding-window two-pointers hashmap
+40 pts 40m
Linked Lists hard

Drop the tail node

Return a new list without the last node.

linked-list lists pointers
+35 pts 30m
Linked Lists hard

Join node values with arrows

Format string node values as 'a -> b -> c'; empty list returns ''.

linked-list lists pointers
+35 pts 30m

Showing 1–9 of 9 challenges · hard

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

  1. Pick a category — basics, algorithms, strings, and more
  2. Open a challenge, read the statement, and edit the starter code
  3. 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.