题解 | 岛屿数量 leetcode 220

#
# 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

  题解：https://leetcode.cn/problems/number-of-islands/solutions/13103/dao-yu-shu-liang-by-leetcode/
#
class Solution:
    def solve(self , grid: List[List[str]]) -> int:
        # write code here
        n_row=len(grid)
        n_col=len(grid[0])
        if n_row==0 or n_col==0:
            return 0
        
                
        def dfs(grid ,row,col):
            grid[row][col]=0
            n_row=len(grid)
            n_col=len(grid[0])
            for x, y in [[row+1,col],[row-1,col],[row,col+1],[row,col-1]]:
                if 0<=x<n_row and 0<=y<n_col and grid[x][y]=='1':
                    dfs(grid,x,y)
        count=0
        for i in range(n_row):
            for j in range(n_col):
                if grid[i][j]=='1':
                    count+=1
                    dfs(grid,i,j)
        return count