Remove duplicates (sorted)
Return a sorted list with duplicates removed.
Merge two sorted arrays
Merge two sorted arrays into one sorted array.
Second Largest Unique Value
Return the second largest distinct integer from a list, or None if it doesn't exist.
Find Missing Number 1 to n
Given a list containing n-1 distinct integers from 1 to n, find the missing number without using extra space.
Majority Element Finder
Implement a function that returns the majority element in a list, which appears more than half the time.
Rearrange Positives and Negatives
Write a function that rearranges a list in-place so all negative numbers come before non-negative numbers.
Wave sort array
Given a list of integers, reorder it into a wave pattern where elements alternate down-up, and return the new list.
Counting Sort
Implement the counting sort algorithm to sort a list of non-negative integers in O(n + k) time.
Showing 8 challenges · easy · Lists & Arrays
Lists & Arrays — Python coding challenges
What you will find here
This page lists lists & arrays 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.