Number of IslandsMedium

Number of Islands

Medium 27.6k58% acceptance

GraphDepth-First SearchArray

Given an m × n grid of '1' (land) and '0' (water), return the number of islands. An island is land connected 4-directionally and surrounded by water.

Example 1

Input: grid = [["1","1","0"],["1","0","0"],["0","0","1"]]

Output: 2

Constraints

1 ≤ m, n ≤ 300
grid[i][j] is '0' or '1'.

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JavaScript

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Case 1

[["1","1","0"],["1","0","0"],["0","0","1"]]

expected: 2

Case 2

[["1","1","1","1","0"],["1","1","0","1","0"],["1","1","0","0","0"],["0","0","0","0","0"]]

expected: 1

Case 3

[["1","1","0","0","0"],["1","1","0","0","0"],["0","0","1","0","0"],["0","0","0","1","1"]]

expected: 3

Case 4

[["1","0","1","0","1"]]

expected: 3

Case 5

[["0","0","0"],["0","0","0"]]

expected: 0

Case 6

[["1","1"],["1","1"]]

expected: 1