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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

Data Structures & Algorithms easy

Index of peak element

Implement a function that returns the index of any peak element in a given integer array.

arrays search peak

Data Structures & Algorithms medium

Find Peak Element

Implement a function that returns the index of any peak element in an integer array.

arrays search binary-search

Data Structures & Algorithms medium

Longest Consecutive Sequence

Given an unsorted list of integers, find the length of the longest consecutive elements sequence in O(n) time.

hash set array linear

Data Structures & Algorithms easy

Pascal Triangle Row

Given a non-negative integer n, return the nth row of Pascal's triangle as a list of integers.

math combinatorics arrays

Data Structures & Algorithms medium

Radix Sort

Implement LSD radix sort to sort a list of non-negative integers in ascending order.

radix-sort sorting counting-sort

Data Structures & Algorithms easy

Find Peak Index

Given a list of integers, return the index of any peak element where the value is not smaller than its neighbors.

arrays linear-scan peak

Data Structures & Algorithms easy

Peak Element in Array

Implement a function that returns the index of any peak element in a list of integers.

array search indices

Data Structures & Algorithms easy

Argsort Indices

Implement a function that returns the indices that would sort a list of integers, with ties broken by original order.

sorting indices lists

Data Structures & Algorithms medium

Arithmetic Slices Count

Given a list of integers, count how many contiguous subarrays of length at least 3 form an arithmetic sequence.

arrays arithmetic counting

Data Structures & Algorithms medium

Strobogrammatic number II

Given a positive integer n, return all strobogrammatic numbers of length n in ascending order.

strings recursion number

Showing 1–10 of 10 challenges · Data Structures & Algorithms

Data Structures & Algorithms — Python coding challenges

What you will find here

This page lists data structures & algorithms challenges — real Python problems you solve in the browser IDE with instant test feedback. Each challenge includes a clear brief, starter code, and automated checks.

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.