大佬求解！！python代码，只过了一个点

from collections import deque
def bfs_ym(n,matrix):  #淹没岛屿
    visited = [[False]*n for _ in range(n)]
    visited[0][0] = True
    directions = [(0,1),(0,-1),(1,0),(-1,0)]
    queue = deque([(0,0)])
    while queue:
        x,y = queue.popleft()
        for dx,dy in directions:
            nx,ny = x+dx,y+dy
            if 0 <= nx < n and 0<= ny < n and not visited[nx][ny]:
                visited[nx][ny] = True
                if matrix[nx][ny] == '#':
                    for dx,dy in directions:
                        nnx,nny = nx+dx,ny+dy
                        if 0 <= nnx < n and 0 <= nny < n and matrix[nnx][nny] == '.':
                            matrix[nx][ny] = '*'
                queue.append((nx,ny))
    return matrix

def bfs_num(matrix_ym,n,x,y):  #相连的岛屿替换为*，防止重复计算
    directions = [(0,1),(0,-1),(1,0),(-1,0)]
    queue = deque([(x,y)])
    while queue:
        x,y = queue.popleft()
        for dx,dy in directions:
            nx,ny = x+dx,y+dy
            if 0 <= nx < n and 0 <= ny < n and matrix_ym[nx][ny] == '#':
                matrix[nx][ny] = '*'
                queue.append((nx,ny))

n = int(input())
matrix = [list(input()) for _ in range(n)]
matrix_ym = bfs_ym(n,matrix)  #淹没之后的岛屿

result = 0  #结果
for i in range(n):
    for j in range(n):
        if matrix_ym[i][j] == '#':
            result +=1
            bfs_num(matrix_ym,n,i,j)
print(result)