Number of Islands

num_of_islands.go

func numIslands(grid [][]byte) int {
    if grid == nil {
        return 0
    }
    
    var numOfIslands int
    
    for i := 0; i < len(grid); i++ {
        for j := 0; j < len(grid[0]); j++ {
            if grid[i][j] == '1' {
                deleteIsland(grid, i, j)
                numOfIslands++
            }
        }   
    }
    return numOfIslands
}

func deleteIsland(grid [][]byte, i int, j int) {
    if i < 0 || j < 0 || i >= len(grid) || j >= len(grid[0]) {
        return
    }
    if grid[i][j] == '1' {
        grid[i][j] = '0'
        deleteIsland(grid, i+1, j)
        deleteIsland(grid, i-1, j)
        deleteIsland(grid, i, j-1)
        deleteIsland(grid, i, j+1)
    }
    return
}