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Python Coding
Challenges

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925 challenges 556 easy 323 medium 46 hard

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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

Python Basics medium

Basic Calculator

Implement a function that evaluates a simple arithmetic expression with +, -, *, / and parentheses.

calculator parsing math

Strings & Text hard

Basic Calculator III

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

parsing string expression

Strings & Text medium

Minimum Remove Valid Parentheses

Given a string with parentheses and letters, remove the fewest parentheses to make it valid.

strings stack validation

Data Structures & Algorithms easy

Valid parentheses

Return True if brackets in the string close in the correct order.

Regular Expressions easy

Match Balanced Parentheses with Regex

Write a function that uses regular expressions to determine if parentheses are balanced and properly nested.

regex strings validation

Recursion & Backtracking medium

Generate Parentheses

Given n, generate all valid strings of n pairs of parentheses.

backtracking recursion parentheses

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

Stacks & Queues medium

Score of Parentheses

Given a balanced parentheses string, compute its score where () is 1 and concatenation sums, nesting multiplies by 2.

stack string parsing

Showing 1–8 of 8 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.