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
Graphs & Graph Algorithms medium

Possible bipartition

Given N people and a list of mutual dislikes, check if they can be divided into two groups with no dislike inside a group.

bipartite graph bfs
+25 pts 25m
Graphs & Graph Algorithms medium

Android unlock patterns

Count the number of valid Android unlock patterns of a given length using a 3x3 grid with adjacency constraints.

graphs dfs backtracking
+25 pts 30m
Graphs & Graph Algorithms medium

Most stones removed

Given stone coordinates on a grid, find the maximum number of stones that can be removed while every stone shares a row or column with another remaining stone.

graphs dfs union-find
+30 pts 30m
Recursion & Backtracking medium

Word Search Backtrack

Determine if a given word exists in a 2D board by tracing adjacent cells without reusing any cell.

backtracking matrix dfs
+25 pts 25m
Matrix & 2D Arrays medium

Number of Islands

Given a 2D grid of '1' (land) and '0' (water), count the number of islands surrounded by water.

matrix graph bfs
+25 pts 30m
Matrix & 2D Arrays medium

Max Area of Island

Given a 2D grid of 0s and 1s, find the maximum area of a connected group of 1s.

grid dfs connected-components
+20 pts 25m
Matrix & 2D Arrays medium

Number of Islands in a Matrix

Count the number of distinct islands (connected groups of 1s) in a 2D binary matrix.

matrix dfs bfs
+20 pts 20m
Matrix & 2D Arrays medium

Word Search Matrix

Given a 2D board and a word, determine if the word can be formed by sequentially adjacent cells (horizontally or vertically), without reusing cells.

matrix dfs strings
+25 pts 30m
Matrix & 2D Arrays medium

Pacific Atlantic Matrix DFS

Given a matrix of heights, return cells that can reach both Pacific and Atlantic oceans using a DFS approach.

dfs matrix traversal
+20 pts 20m
Matrix & 2D Arrays medium

Regions Cut by Slashes

Given a grid of slashes, count the number of connected regions formed by the slashes and the grid borders.

grid dfs union-find
+30 pts 30m

Showing 25–34 of 34 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

  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.