Rescue HDU1242

裸的优先队列bfs  学会了优先队列  

很快写好   但是debug了半个小时 就是应为while里面加了，（a+b)  导致无限超时！！！

优先队列 

struct node
{
    int x,y,d;
    node(int x=0,int y=0,int d=0):x(x),y(y),d(d){}
  friend bool operator < (node n1,node n2)
    {
        return n2.d<n1.d;
    }
};

 priority_queue<node> q;

#include<bits/stdc++.h>
using namespace std;

int n,m,sx,sy;
char m1[500][500];
bool f[500][500];
bool flag=false;

struct node
{
    int x,y,d;
    node(int x=0,int y=0,int d=0):x(x),y(y),d(d){}
  friend bool operator < (node n1,node n2)
    {
        return n2.d<n1.d;
    }
};

void bfs()
{
    int dx[4]={0,1,0,-1};
    int dy[4]={1,0,-1,0};
    memset(f,false,sizeof(f));

    node u(sx,sy,0);
    priority_queue<node> q;
    //queue<node>q;
    q.push(u);
    while(!q.empty())
    {
        node u=q.top();q.pop();
       // printf("%d %d %d
",u.x,u.y,u.d);
        if(m1[u.x][u.y]=='r') {printf("%d
",u.d);return;}

        for(int i=0;i<4;i++)
        {
            node v(u.x+dx[i],u.y+dy[i],u.d+1);

            if(v.x>=1&&v.x<=n&&v.y>=1&&v.y<=m&&m1[v.x][v.y]!='#'&&!f[v.x][v.y])
            {
                if(m1[v.x][v.y]=='x')
                {
                    f[v.x][v.y]=true;v.d++; q.push(v);


                }
                else if((m1[v.x][v.y]=='r'||m1[v.x][v.y]=='.'))
                {
                    f[v.x][v.y]=true; q.push(v);

                }

            }

        }
    }

  printf("Poor ANGEL has to stay in the prison all his life.
");


}





int main()
{


    while(scanf("%d%d",&n,&m)==2)
    {



        for(int i=1;i<=n;i++)
           {
               scanf("%s",m1[i]+1);

               for(int j=1;j<=m;j++)
               {if(m1[i][j]=='a'){sx=i;sy=j; }
                }
           }




          bfs();
    }






    return 0;
}