count-sub-islands.py

class Solution:
    def countSubIslands(self, grid1: List[List[int]], grid2: List[List[int]]) -> int:
        m = len(grid1)
        n = len(grid1[0])
        res = 0

        def dfs(grid, i, j):
            m = len(grid)
            n = len(grid[0])
            if i < 0 or j < 0 or i >= m or j >= n:
                return
            if 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)
        for i in range(m):
            for j in range(n):
                if grid1[i][j] == 0 and grid2[i][j] == 1:
                    dfs(grid2, i, j)
        for i in range(m):
            for j in range(n):
                if grid2[i][j] == 1:
                    res += 1
                    dfs(grid2, i, j)
        return res