Rescue--hdu1242

题目链接：

http://acm.hdu.edu.cn/showproblem.php?pid=1242

运用优先队列进行广搜

#include <stdio.h>
#include<iostream>
#include <string.h>
#include <queue>
#include <algorithm>
#define inf 0x6ffffff
#define N 220
using namespace std;

int n,m,vis[N][N];
int dir[4][2]={ {0,1},{0,-1},{1,0},{-1,0} };
char maps[N][N];

struct node
{
    int x,y,step;
    friend bool operator < (node a,node b)
    {
        return a.step > b.step;
    }
};
bool judge(int x,int y)
{
    return x<n&&x>=0&&y>=0&&y<m&&vis[x][y]==0&&maps[x][y]!='#';
}
int bfs(node s,node e)
{
    memset(vis,0,sizeof(vis));
    node q;
    priority_queue<node> Q;
    Q.push(s);
    vis[s.x][s.y]=1;
    while(!Q.empty())
    {
        q=Q.top();
        Q.pop();
        if(q.x==e.x&&q.y==e.y)
            return q.step;

        for(int i=0;i<4;i++)
        {
            s.x=q.x+dir[i][0];
            s.y=q.y+dir[i][1];
            if(judge(s.x,s.y))
            {
                if(maps[s.x][s.y]=='x')
                    s.step=q.step+2;
                else
                    s.step=q.step+1;
                vis[s.x][s.y]=1;
                Q.push(s);
            }
        }
    }
    return -1;
}

int main()
{
    int i,j,ans;
    node s,e;
    while(scanf("%d%d",&n,&m)!=EOF)
    {
        memset(maps,0,sizeof(maps));
        for(i=0;i<n;i++)
        {
            for(j=0;j<m;j++)
            {
                cin>>maps[i][j];
                if(maps[i][j]=='a')
                    s.x=i,s.y=j;
                if(maps[i][j]=='r')
                    e.x=i,e.y=j;
            }
        }
        s.step=0;

        ans=bfs(s,e);

        if(ans==-1)
            printf("Poor ANGEL has to stay in the prison all his life.
");
        else
            printf("%d
",ans);
    }
    return 0;
}