题解 | #岛屿数量#

#
# 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
#
# 判断岛屿数量
# @param grid char字符型二维数组
# @return int整型
#
class Solution:
    def solve(self, grid: List[List[str]]) -> int:
        # write code here
        nr = len(grid)
        if nr == 0:
            return 0
        nc = len(grid[0])

        def dfs(r: int, c: int) -> None:
            grid[r][c] = 0
            for x, y in [(r - 1, c), (r + 1, c), (r, c - 1), (r, c + 1)]:
                if 0 <= x < nr and 0 <= y < nc and grid[x][y] == "1":
                    dfs(x, y)

        num_islands = 0
        for r in range(nr):
            for c in range(nc):
                if grid[r][c] == "1":
                    num_islands += 1
                    dfs(r, c)
        return num_islands