题解 | #岛屿数量#

class Solution:
    def solve(self, grid):
        if not grid:
            return 0

        rows = len(grid)
        cols = len(grid[0])
        count = 0

        def dfs(row, col):
            if (
                row < 0
                or row >= rows
                or col < 0
                or col >= cols
                or grid[row][col] != "1"
            ):
                return

            grid[row][col] = "#"  # 标记当前陆地已经访问过，避免重复计数

            # 递归地探索相邻的陆地
            dfs(row - 1, col)  # 上
            dfs(row + 1, col)  # 下
            dfs(row, col - 1)  # 左
            dfs(row, col + 1)  # 右

        # 遍历整个矩阵
        for row in range(rows):
            for col in range(cols):
                if grid[row][col] == "1":
                    count += 1  # 发现一个新的岛屿
                    dfs(row, col)  # 使用DFS遍历该岛屿的所有陆地

        return count