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
#
from collections import deque
class Solution:
    def solve(self , grid: List[List[str]]) -> int:
        # write code here
        n = len(grid)
        m = len(grid[0])
        visited = set()
        count = 0
        directions = [(1,0),(-1,0),(0,1),(0,-1)]
        for i in range(n):
            for j in range(m):
                if grid[i][j] == "1" and (i,j) not in visited:
                    count += 1
                    visited.add((i,j))
                    queue = deque()
                    queue.append((i,j))
                    while queue:
                        ni,nj = queue.popleft()
                        for di,dj in directions:
                            newi,newj = ni + di,nj +dj
                            if 0 <= newi < n and 0 <= newj < m:
                                if grid[newi][newj] == "1" and (newi,newj) not in visited:
                                    visited.add((newi,newj))
                                    queue.append((newi,newj))
        return count