NYOJ 635优先队列

 
#include<iostream>
#include<algorithm>
#include<queue>
#include<cstdio>
#include<cstring>
using namespace std;
char f[52][52];
bool vis[52][52];
int Ex,Ey,N,M;
const int dir[4][2]={-1,0,1,0,0,1,0,-1};
struct Data
{int time;
int x,y;};
struct cmp
{
    bool operator() (Data a,Data b)
    {
        return a.time>b.time;
    }
};
priority_queue<Data,vector<Data>,cmp>Q;
void BFS()
{
    while(!Q.empty())Q.pop();
    memset(vis,0,sizeof(vis));
    Data t,elem;
    t.time=0;t.x=t.y=1;Q.push(t);
    int nx,ny;vis[1][1]=true;
    while(!Q.empty())
    {
        t=Q.top();Q.pop();
        if(t.x==Ex&&t.y==Ey){printf("%d\n",t.time);break;}
        for(int i=0;i<4;i++)
        {
            nx=t.x+dir[i][0];
            ny=t.y+dir[i][1];
            if(nx>0&&nx<=N&&ny>0&&ny<=M&&!vis[nx][ny])
            {
                elem.time=t.time+(f[nx][ny]=='#'?4:1);
                elem.x=nx;elem.y=ny;
                Q.push(elem);
                vis[nx][ny]=true;
            }     
        } 
    }
}
int main()
{   
    while(~scanf("%d%d",&N,&M))
    {
        for(int i=1;i<=N;i++)
            scanf("%s",f[i]+1);
        scanf("%d%d",&Ex,&Ey);
        BFS();
    }
}