Practice Arena

Python Coding Challenges

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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

Bellman-Ford Algorithm

Implement the Bellman-Ford algorithm to compute shortest distances from a source in a directed weighted graph with up to 100 vertices and negative edges.

shortest-path negative-edges graph
+30 pts 30m
Graphs & Graph Algorithms medium

Prim's Minimum Spanning Tree

Given a connected undirected weighted graph, compute the total weight of its minimum spanning tree using Prim's algorithm.

graphs mst prim
+30 pts 30m
Graphs & Graph Algorithms medium

Kruskal MST

Implement Kruskal's algorithm to compute the total weight of a minimum spanning tree in a connected undirected graph.

graphs minimum-spanning-tree union-find
+25 pts 30m
Graphs & Graph Algorithms medium

Strongly Connected Components (Kosaraju's Algorithm)

Implement a function to find strongly connected components in a directed graph using Kosaraju's algorithm.

graphs dfs kosaraju
+30 pts 30m
Graphs & Graph Algorithms medium

Floyd-Warshall: All-Pairs Shortest Paths

Implement the Floyd-Warshall algorithm to find all-pairs shortest path distances in a directed graph with possibly negative weights but no negative cycles.

graph shortest-path dynamic-programming
+25 pts 30m
Recursion & Backtracking hard

Hamiltonian Cycle Backtrack

Implement a backtracking algorithm to find a Hamiltonian cycle in an undirected graph.

backtracking graph hamiltonian
+45 pts 40m
Binary Search hard

Median of Sorted Array BS

Implement a binary search algorithm to find the median of two sorted arrays efficiently.

binary-search arrays median
+45 pts 35m
Two Pointers & Sliding Window medium

Sort Colors (Dutch National Flag)

Implement the Dutch National Flag algorithm to sort an array of 0, 1, 2 in one pass.

in-place two-pointers sorting
+20 pts 25m
Two Pointers & Sliding Window hard

Minimum Window Substring

Implement a sliding window algorithm to find the minimum window substring containing all characters of a given pattern.

sliding-window two-pointers strings
+45 pts 35m
Stacks & Queues easy

Max Stack Design

Implement a MaxStack class with push, pop, top, and get_max operations.

stack design max
+10 pts 15m
Datetime & Time Calculations medium

Julian Day Number Converter

Implement two functions to convert between Gregorian calendar dates and Julian Day Numbers using a standard formula.

datetime date-arithmetic algorithms
+20 pts 20m
Datetime & Time Calculations medium

Easter Date Calculator

Implement a function that returns the date of Easter Sunday for a given year using the Gregorian computus algorithm.

datetime date easter
+20 pts 25m

Showing 25–36 of 36 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.