FZU2150 Fire Game

AC代码：

#include <iostream>
#include <cstdio>
#include <cstring>
#include <string>
#include <queue>
#include <vector>
#include <algorithm>
#define INF 0x3f3f3f3f
using namespace std;

struct node{
    int x,y,t;
    //用优先队列一直超时
};
const int dx[] = {-1,0,1,0},dy[] = {0,-1,0,1};
char maze[15][15];
int vis[15][15];
int n,m;

int bfs(node a,node b){
    memset(vis,0,sizeof(vis));
    queue<node> q;
    node cur;
    vis[a.x][a.y] = vis[b.x][b.y] = 1;
    q.push(a);q.push(b);
    int ans = 0;
    while(!q.empty()){
        cur = q.front();
        q.pop();
        ans = max(ans,cur.t);
        for(int i = 0; i < 4; i++){
            int xx = cur.x+dx[i],yy = cur.y+dy[i];
            if(xx < 0 || xx >= n || yy < 0 || yy >= m || maze[xx][yy] != '#' || vis[xx][yy])
                continue;
            vis[xx][yy] = 1;
            q.push((node){xx,yy,cur.t+1});
        }
    }
    for(int i = 0; i < n; i++){
        for(int j = 0; j < m; j++){
            if(maze[i][j] == '#' && !vis[i][j]){
                return INF;
            }
        }
    }
    return ans;
}

int main(){
    int T,t = 1;
    scanf("%d",&T);
    while(T--){
        vector<node> v;
        int cnt = 0;
        scanf("%d%d",&n,&m);
        for(int i = 0; i < n; i++){
            scanf("%s",maze[i]);
            for(int j = 0; j < m; j++){
                if(maze[i][j] == '#'){
                    cnt++;
                    v.push_back((node){i,j,0});
                }
            }
        }
        printf("Case %d: ",t++);
        int ans = INF;
        for(int i = 0; i < cnt; i++){
            for(int j = i; j < cnt; j++){
                ans = min(ans,bfs(v[i],v[j]));
            }
        }
        if(ans == INF)
            printf("-1\n");
        else
            printf("%d\n",ans);
    }
    return 0;
}