题解 | 数水坑

n,m = input().split(" ")
n,m = int(n),int(m)
matrix = []
for i in range(n): 
    a = list(input())
    matrix.append(a)
count = 0
visited = [[False]*m for _ in range(n)]
def dfs(r,c):
    if r<0 or c<0 or r>n-1 or c>m-1 or visited[r][c] or matrix[r][c] == ".":
        return
    visited[r][c] = True
    dfs(r-1, c)
    dfs(r+1, c)
    dfs(r, c-1)
    dfs(r, c+1)
    dfs(r-1, c-1)
    dfs(r-1, c+1)
    dfs(r+1, c-1)
    dfs(r+1, c+1)
for i in range(n):
    for j in range(m):
        if matrix[i][j] == "W" and not visited[i][j]:
            dfs(i,j)
            count += 1
print(count)