leetcode(14)DFS系列题目

200. 岛屿数量

class Solution:
    def numIslands(self, grid: List[List[str]]) -> int:
        def dfs(grid, i, j):
            if not 0 <= i < len(grid) or not 0 <= j < len(grid[0]) or grid[i][j] == '0':
                return
            grid[i][j] = '0'
            dfs(grid, i + 1, j)
            dfs(grid, i - 1, j)
            dfs(grid, i, j - 1)
            dfs(grid, i, j + 1)
        count = 0
        for i in range(len(grid)):
            for j in range(len(grid[0])):
                if grid[i][j] == '1':
                    dfs(grid, i, j)
                    count += 1
        return count

695. 岛屿的最大面积

class Solution:
    def maxAreaOfIsland(self, grid: List[List[int]]) -> int:
        def dfs(grid, i, j):
            # 遇到边界或者遇到0了，就停止
            if not 0 <= i < len(grid) or not 0 <= j