HDOJ 1242 RescueRescue

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我是靠谱客的博主拼搏巨人，最近开发中收集的这篇文章主要介绍HDOJ 1242 RescueRescue，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

Rescue

Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 22897 Accepted Submission(s): 8103

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

Author

CHEN, Xue

Source

ZOJ Monthly, October 2003

bfs+优先队列!折腾了将近三个小时终于差不多能把这道题写出来了。

代码如下：

#include<cstdio>
#include<queue>
using namespace std;
int N,M,a_x,a_y,r_x,r_y;
char Map[250][250];
int dis[4][2]={{-1,0},{1,0},{0,-1},{0,1}};
struct Note
{
int x,y,step;
bool friend operator<(Note x,Note y)
{
return x.step>y.step;
}
}r,temp;
int Judge(Note a)
{
if(a.x>=0&&a.x<N&&a.y>=0&&a.y<M&&Map[a.x][a.y]!='#')
return 1;
else
return 0;
}
int bfs()
{
priority_queue<Note>q;
int i;
r.x=r_x;
r.y=r_y;
r.step=0;
q.push(r);
while(!q.empty())
{
r=q.top();
q.pop();
if(r.x==a_x&&r.y==a_y)
return r.step;
for(i=0;i<4;i++)
{
temp.x=r.x+dis[i][0];
temp.y=r.y+dis[i][1];
if(Judge(temp))
{
if(Map[temp.x][temp.y]=='.'||Map[temp.x][temp.y]=='a')
temp.step=r.step+1;
else
temp.step=r.step+2;
Map[temp.x][temp.y]='#';
q.push(temp);
}
}
}
return -1;
}
int main()
{
while(~scanf("%d%d",&N,&M))
{
for(int i=0;i<N;i++)
{
scanf("%s",Map[i]);
for(int j=0;j<M;j++)
{
if(Map[i][j]=='r')
{
r_x=i;r_y=j;
}
if(Map[i][j]=='a')
{
a_x=i;a_y=j;
}
}
}
int time=bfs();
if(time==-1)
printf("Poor ANGEL has to stay in the prison all his life.n");
else
printf("%dn",time);
}
return 0;
}