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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 easy

Clamp a Number to a Range

Implement a clamp function that returns a value within a specified range.

numbers conditionals comparisons

Python Basics easy

Count down from n

Implement a function that returns a list from n down to 1.

loops range lists

Python Basics easy

Count Multiples in a Range

Given a start, end, and divisor, count how many integers in [start, end] are divisible by the divisor.

multiples range divisibility

Python Basics easy

Range of values

Calculate the range (max minus min) of a list of numbers. Empty list returns 0.

min max numbers

Python Basics easy

Element-wise Clip

Implement a function that clips each element of a list to a specified range.

clipping lists conditionals

Python Basics easy

Min-Max Scaler: Fit and Transform

Implement a MinMaxScaler class that normalizes numeric data to a given range using fit and transform methods.

scaling normalization class

Strings & Text easy

Parse range notation

Parse a comma-separated list of ranges and individual numbers, expanding each range into its full sequence.

strings parsing ranges

Lists & Arrays easy

Move Zeros to End

Rearrange a list by moving all zeros to the end while preserving the relative order of non-zero elements.

list in-place two-pointer

Lists & Arrays easy

Rearrange Positives and Negatives

Write a function that rearranges a list in-place so all negative numbers come before non-negative numbers.

in-place two-pointers partition

Lists & Arrays easy

Wave sort array

Given a list of integers, reorder it into a wave pattern where elements alternate down-up, and return the new list.

sorting swap rearrangement

Lists & Arrays easy

Normalize Array to Zero-One Range

Implement a function that normalizes a list of numbers to the range [0,1] using min-max scaling.

arrays normalization scaling

Iterators & Generators easy

Range-like generator

Implement a custom generator that yields numbers like Python's range but with flexible bounds.

generator yield range

Dynamic Programming easy

Derangement count

Implement a function to count derangements of n items using the classic recurrence.

dynamic-programming combinatorics recursion

Trees & Binary Trees easy

Range Sum BST

Return the sum of all node values in a BST that lie within a given inclusive range [low, high].

bst tree recursion

Binary Search easy

Find Indices of Target in Sorted List

Given a sorted list and a target, return the indices of its first and last occurrence, or [-1, -1] if absent.

binary-search sorted range

Binary Search easy

First Bad Version

Implement a function to find the first bad version in a sorted range using binary search.

binary-search search array

Linked Lists easy

Value at index n

Return the value at zero-based index n or None if out of range.

linked-list lists pointers

Datetime & Time Calculations easy

Leap Years in Range

Write a function that returns a list of all leap years between two given years, inclusive.

leap-year range datetime

Numpy & Vectorized Computing easy

Clip vector to range

Clamp each value to [lo, hi].

vectors arrays numpy-style

Showing 1–19 of 19 challenges · easy

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.