medium

Number of Islands

A grid contains 1 for land and 0 for water. An island is a maximal group of land cells connected horizontally or vertically. Count the islands.

Constraints
  • 1 ≤ m, n ≤ 300
  • grid[i][j] ∈ {0, 1}
Examples
in: grid = [["1","1","0","0"],["1","0","0","1"],["0","0","1","1"]]
out: 3

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