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

Dynamic Programming medium

Word Break DP

Implement a function to check if a string can be segmented into space-separated dictionary words.

dynamic-programming strings word-break

Trees & Binary Trees medium

Vertical Order Traversal

Compute the vertical order traversal of a binary tree, grouping nodes by column and row.

binary-tree bfs dictionary

Graphs & Graph Algorithms medium

Alien Dictionary Order

Given a sorted list of words in an alien language, derive the order of its unique letters.

graph topological-sort string

Datetime & Time Calculations easy

Age in years months days

Given birth and reference dates, return age as a dictionary with years, months, days.

datetime date arithmetic age calculation

Data Formats & Parsing easy

Protocol definition

Parse a simple wire protocol string into a structured dictionary.

parsing protocol strings

Data Formats & Parsing easy

Config Parser Reader

Parse a simple INI-style configuration text into a nested dictionary.

parsing strings config

Data Formats & Parsing easy

Parse YAML-like dict

Parse a simple YAML-like text with indentation into a nested dictionary.

parsing yaml dictionary

Data Formats & Parsing medium

Flatten nested JSON

Write a function that flattens nested JSON objects into a flat dictionary with dot-separated keys, handling lists and empty objects.

json recursion dictionaries

Data Formats & Parsing medium

Unflatten JSON dict

Given a flat dictionary with keys like 'a.b.c', reconstruct the nested dictionary where each dotted segment becomes a nested level.

json dict parsing

Data Formats & Parsing medium

Serialize dict to TOML-like

Convert nested Python dicts into a simplified TOML-like string with sorted keys, type-aware formatting, and flat table sections.

dict toml serialization

Data Formats & Parsing easy

Parse Apache log line

Write a function that parses a single Apache access log line into a dictionary with IP, timestamp, request, status, and size.

parsing strings regex

Data Formats & Parsing easy

Parse table rows

Implement a function that converts a simple text table into a list of dictionaries.

parsing strings csv

SQL & SQLite easy

Inner Join Two Tables

Write a function that inner joins two lists of dictionaries on a common key and returns the combined rows.

sql join dictionaries

Showing 49–61 of 61 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

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.