2024-04-19 07:37:20 +0000 UTC

func numIslands(grid [][]byte) int {
    if len(grid) == 0 || len(grid[0]) == 0 {
        return 0
    }
    
    rows := len(grid)
    cols := len(grid[0])
    islands := 0
    
    var dfs func(row, col int)
    dfs = func(row, col int) {
        if row < 0 || col < 0 || row >= rows || col >= cols || grid[row][col] != '1' {
            return
        }
        grid[row][col] = '0'
        dfs(row-1, col)
        dfs(row+1, col)
        dfs(row, col-1)
        dfs(row, col+1)
    }
    
    for row := 0; row < rows; row++ {
        for col := 0; col < cols; col++ {
            if grid[row][col] == '1' {
                dfs(row, col)
                islands++
            }
        }
    }
    
    return islands
}