Max Area of Island

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Problem

Given a binary grid where 1 represents land and 0 represents water, return the area of the largest island — a group of 1s connected horizontally or vertically. Return 0 if there is no island.

Examples

Example 1

Input:grid with one connected region of six 1s

Output:6

Constraints

1 <= m, n <= 50

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How to approach it: the Graphs pattern

A graph models relationships as nodes and edges, which can be directed or undirected, weighted or not. Most graph problems come down to choosing the right traversal — DFS, BFS, or union-find — for what you're trying to find.

Look for this pattern when

The problem involves connections between items (islands, courses with prerequisites, friend networks, grids).
You need the shortest path in an unweighted graph (BFS) or need to explore every reachable node (DFS).
You're asking "are these two things connected?" repeatedly (union-find).

Read the full Graphs guide →

Video walkthroughs

Original problem on LeetCode ↗