You are given an m x n binary matrix grid. An island is a group of 1s (land) connected 4-directionally (horizontal or vertical).
Return the area of the largest island. If there is no island, return 0.
We use analytics and advertising cookies to understand how the site is used and whether our ads on Facebook and Instagram work. They are set only if you accept. See our Privacy Policy for details.
You are given an m x n binary matrix grid. An island is a group of 1s (land) connected 4-directionally (horizontal or vertical).
Return the area of the largest island. If there is no island, return 0.
A medium graphs problem, graded against 5 test cases (3 of them hidden).
Nodes and edges - traversal, connectivity, cycles, and shortest paths.
Reach for it when you see: Explicit edges, a grid treated as a graph, or dependencies between items.
More Graphs problems →DFS flood-fill. From each land cell, recurse into its four neighbors, marking cells as visited by zeroing them, and sum the cells reached. The largest such sum is the answer.
Time: O(m·n) - each cell is visited once.
Space: O(m·n) recursion stack in the worst case.
The full reference solution in every supported language stays in the editor above - reveal it there once you have had a real attempt.
Read off this problem's own test suite, so these are the cases a submission actually has to survive.
These apply to the pattern as a whole, not just this problem.