200.岛屿数量

leetcode

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时间复杂度：O(MN)
空间复杂度：O(MN)

func numIslands(grid [][]byte) int {
    result := 0

    var dfs func(int, int, int)

    dfs = func(row int, col int, count int){
        if row < 0 || col < 0 || row >= len(grid) || col >= len(grid[0]) {
            return
        }

        if string(grid[row][col]) == "0" || string(grid[row][col]) == "2" {
            return
        }

        // if count > 0 {
        //     fmt.Printf("grid: %v\n", grid)
        // }
        grid[row][col] = '2'
        result += count

        dfs(row - 1, col, 0) //上
        dfs(row, col + 1, 0) //右
        dfs(row + 1, col, 0) //下
        bfs(row, col - 1, 0) //左
    }

    for i := 0; i < len(grid); i++ {
        for j := 0; j < len(grid[0]); j++ {
            bfs(i, j, 1)
        }
    }

    return result
}