hdu-1242 Rescue

本题用到了了搜索和队列，第一次将这两个加起来写，有点吃力。。。。。。

队列相关知识：http://blog.csdn.net/zxy_snow/article/details/6118988

#include<stdio.h>
#include<string.h>
#include<queue> 
#include<algorithm>
using namespace std;
int map[220][220];
int a_x,a_y,b_x,b_y,n,m;
int top[4][2]={{0,-1},{0,1},{1,0},{-1,0}};  //上下搜索的四个点 
struct node{//自定义的队列 
	int x; int y;
	int step;
	friend bool operator < (node n1,node n2){
		return n2.step < n1.step;
	}
};
int judge(int x,int y){//判断执行条件 
	if(x < 0 || x >= n || y < 0 || y >= m)
	   return 1;
	if(map[x][y] == 1)
	   return 1;
	return 0;
}
int bfs(){//搜索 
	priority_queue<node>q;
	node cur,next;
	int i;
	
	cur.x = b_x;
	cur.y = b_y;
	cur.step = 0;
	map[cur.x][cur.y] = 1;
	q.push(cur);
	while(!q.empty()){
		cur = q.top();
		q.pop();
		if(cur.x == a_x && cur.y == a_y)
		    return cur.step;
		    
		for(i = 0;i < 4;i++){
			next.x = cur.x + top[i][0];
			next.y = cur.y + top[i][1];
			if(judge(next.x,next.y))
			    continue;
			if(map[next.x][next.y] == -1)
			   next.step = cur.step + 2;
			else
			   next.step = cur.step + 1;
			map[next.x][next.y] = 1;
			q.push(next);
		}
		
	}
	return -1;
}
int main(){
	int i,j,k,t;
	char str[220];
	while(~scanf("%d %d",&n,&m)){
		memset(map,0,sizeof(map));
	    for(i=0;i<n;i++){
	    	scanf("%s",str);
	    	for(j=0;str[j];j++){
	    		if(str[j] == 'a'){//标记带搜索的位置 
	    			a_x = i;
	    			a_y = j;
	    		}
	    		else if(str[j] == 'r'){//标记开始搜索的位置 
	    			b_x = i;
	    			b_y = j;
	    		}
	    		else if(str[j] == '#')
	    		   map[i][j] = 1;//将为墙的标记为1 
	    		else if(str[j] == '.')
	    		   map[i][j] = 0;//将为道路的标记为0 
	    		else if(str[j] == 'x')
	    		   map[i][j] = -1;//将为敌人的标记为-1 
	    	}
	    	
	    }
	    int ans = bfs();
	    if(ans == -1)
	        printf("Poor ANGEL has to stay in the prison all his life.\n");
	    else
	        printf("%d\n",ans);
	}
	return 0;
}