leetcode200.岛屿数量

func numIslands(grid [][]byte) int {
    res:=0
    for i:=0;i<len(grid);i++{
        for j:=0;j<len(grid[0]);j++{
            if grid[i][j]=='1'{
                res++

                dfs(grid,i,j)
            }
        }
    }
    return res
    
}

func dfs(grid [][]byte,i,j int){
    m,n:=len(grid),len(grid[0])

    if i<0||j<0 || i>=m ||j>=n{
        return
    }
    if grid[i][j]=='0'{
        return
    }
    grid[i][j]='0'

    dfs(grid,i+1,j)
    dfs(grid,i,j+1)
    dfs(grid,i-1,j)
    dfs(grid,i,j-1)
}