Number of Islands
Given a 2D grid of '1' (land) and '0' (water), count the number of islands surrounded by water.
Pacific Atlantic Flow
Given a height matrix, return all cells from which water can flow to both the Pacific and Atlantic oceans.
Showing 1–2 of 2 challenges · Matrix & 2D Arrays
Matrix & 2D Arrays — Python coding challenges
What you will find here
This page lists matrix & 2d 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.