穿越隧道

#include <bits/stdc++.h>
using namespace std;
#define x first
#define y second
typedef pair<int,int> pii;
const int N = 1e3 + 10, M = N * N;
char g[N][N];
bool st[N][N];
pii q[M];
int n,m;
int ans;
void dfs(int a, int b){
    q[0] = {a,b};
    st[a][b] = true;
    int hh = 0, tt = 0;
    while(hh <= tt){
        pii t = q[hh++];
        for(int i = t.x - 1; i <= t.x + 1; i ++){
            for(int j = t.y - 1; j <= t.y + 1; j++){
                if(i == t.x && j == t.y) continue;
                if(g[i][j] == '.' || st[i][j]) continue;
                if(i < 0 || i >= n || j < 0 || j >= m) continue;
                st[i][j] = true;
                q[++tt] = {i,j};
            }
        }
    }
}
int main(){
    scanf("%d%d",&n,&m);
    for(int i = 0; i < n; i++) scanf("%s",g[i]);
    
    for(int i = 0; i < n; i++){
        for(int j = 0; j < m; j++){
            if(g[i][j] == 'W' && !st[i][j]){
                dfs(i,j);
                ans++;
            }
        }
    }
    printf("%d\n",ans);
    return 0;
}