HDU1242Rescue

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概述

Rescue

Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 27043 Accepted Submission(s): 9576

Problem Description

Angel was caught by the MOLIGPY! He was put in prison by Moligpy. The prison is described as a N * M (N, M <= 200) matrix. There are WALLs, ROADs, and GUARDs in the prison.

Angel's friends want to save Angel. Their task is: approach Angel. We assume that "approach Angel" is to get to the position where Angel stays. When there's a guard in the grid, we must kill him (or her?) to move into the grid. We assume that we moving up, down, right, left takes us 1 unit time, and killing a guard takes 1 unit time, too. And we are strong enough to kill all the guards.

You have to calculate the minimal time to approach Angel. (We can move only UP, DOWN, LEFT and RIGHT, to the neighbor grid within bound, of course.)

Input

First line contains two integers stand for N and M.

Then N lines follows, every line has M characters. "." stands for road, "a" stands for Angel, and "r" stands for each of Angel's friend.

Process to the end of the file.

Output

For each test case, your program should output a single integer, standing for the minimal time needed. If such a number does no exist, you should output a line containing "Poor ANGEL has to stay in the prison all his life."

Sample Input

  
  
   
   7 8
#.#####.
#.a#..r.
#..#x...
..#..#.#
#...##..
.#......
........

Sample Output

  
  
   
   13
  
  
  
  
   
   

  
  
  
  
   
   bfs迷宫题，学会使用结构体和方向数组
  
  
  
  
   
   使用优先队列求得最优解~
  
  
  
  
   
   读入图的过程要注意。
  
  
  
  
   
   

  
  
  
  
   
   
   
   #include<iostream>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<queue>
using namespace std;

#define Maxn 205

char mat[Maxn][Maxn];
int vis[Maxn][Maxn];
int dir[4][2]={{-1,0},{1,0},{0,-1},{0,1}};
int row,col;

struct Node
{
	int x,y;
	int time;
    friend bool operator < (const Node &a,const Node &b)  
	{
		return a.time>b.time;
	}
};

Node start;

int bfs(Node source)
{

    memset(vis,0,sizeof(vis));
    priority_queue<Node> q;
    while(!q.empty()) q.pop();
    q.push(source);
    vis[source.x][source.y]=1;
    while(!q.empty())
    {
        int i;
        Node next;
        Node a=q.top();
        q.pop();
        for(i=0;i<4;i++)
        {
            next.x=a.x+dir[i][0];
            next.y=a.y+dir[i][1];
            if(next.x<0||next.x>=row||next.y<0||next.y>=col||mat[next.x][next.y]=='#')
                continue;
            if(vis[next.x][next.y]) continue;
            vis[next.x][next.y]=1;
            if(mat[next.x][next.y]=='x') next.time=a.time+2;
            if(mat[next.x][next.y]=='.') next.time=a.time+1;
            if(mat[next.x][next.y]=='r') {return a.time+1;}
            q.push(next);
        }
    }
    return -1;
}

int main()
{
	int i,j;
	int ans;
	while(scanf("%d%d",&row,&col)!=EOF)
	{
		for(i=0;i<row;i++)
		{
		    for(j=0;j<col;j++)
            {
                cin>>mat[i][j];
                //scanf("%c",&mat[i][j]);为什么用scanf不行？？？
                if(mat[i][j]=='a')
		        {
			        start.x=i;
			        start.y=j;
			        start.time=0;
		        }
            }
            getchar();
		}
		/*for(i=0;i<row;i++)
        {
            for(j=0;j<col;j++)
            {
                cout<<mat[i][j];

            cout<<endl;
        }*/
        ans=bfs(start);
		if(ans==-1)
		printf("Poor ANGEL has to stay in the prison all his life.n");
		else
		printf("%dn",ans);
	}
	return 0;
}