Max Area of Island

medium

You are given an m x n binary matrix grid. An island is a group of 1's (representing land) connected 4-directionally. You may assume all four edges of the grid are surrounded by water.

The area of an island is the number of cells with value 1 in the island.

Return the maximum area of an island in grid. If there is no island, return 0.

Test Cases

Copy an input into the main harness and Run to verify

Input

grid = [[0,0,1,0],[1,1,1,0],[0,1,0,0]]

Expected Output

5

Explanation: The connected block of 1's has area 5.

Input

grid = [[0,0,0],[0,0,0]]

Expected Output

0

Constraints

m == grid.length
n == grid[i].length
1 <= m, n <= 50
grid[i][j] is either 0 or 1.

Hints

Hint 1 — click to reveal

This is Number of Islands, except each flood fill returns a size instead of just counting.

Hint 2 — click to reveal

Sinking each visited cell to 0 is a neat way to avoid a separate visited array.

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