岛屿的数量

两个错误的点：
1.误解题意：题目传进来的不一定是正方形，可能是长方形，所以grid的长度和每行的长度不一致
2.covered函数中如果这个点已经是0就不必再遍历周围的值，也就是它是岛屿的边，遇到边就停

def numIslands(grid):
    def covered(i: object, j: object) -> object:
        nonlocal grid, l,k
        if grid[i][j] == '0':
            return
        grid[i][j] = '0'
        if -1 < i - 1 < l and -1 < j < k and grid[i - 1][j] == '1':
            covered(i - 1, j)
        if -1 < i + 1 < l and -1 < j < k and grid[i + 1][j] == '1':
            covered(i + 1, j)
        if -1 < i < l and -1 < j - 1 < k and grid[i][j - 1] == '1':
            covered(i, j - 1)
        if -1 < i < l and -1 < j + 1 < k and grid[i][j + 1] == '1':
            covered(i, j + 1)
    l = len(grid)
    k = len(grid[0])
    count = 0
    for i in range(l):
        for j in range(k):
            if grid[i][j] == '1':
                print(f'{i}-{j}')
                count += 1
                covered(i, j)
            continue
    return count
grid = [
    ["1", "1", "0", "0", "0"],
    ["1", "1", "0", "0", "0"],
    ["0", "0", "1", "0", "0"],
    ["0", "0", "0", "1", "1"]
]

···