杭电1242--Rescue（BFS+优先队列）

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Problem Description

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

Angel's friends want to save Angel. Their task is: approach Angel.We assume that "approach Angel" is to get to the position whereAngel stays. When there's a guard in the grid, we must kill him (orher?) 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 unittime, too. And we are strong enough to kill all the guards.

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

Input

First line contains two integers stand for N and M.

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

Process to the end of the file.

Output

For each test case, your program should output a singleinteger, standing for the minimal time needed. If such a numberdoes no exist, you should output a line containing "Poor ANGEL hasto stay in the prison all his life."

Sample Input

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

Sample Output

13

# include<stdio.h>
# include<stdlib.h>
# include<string.h>
int num[210][210],n,m,x1,y1,mtime;//num[][]记录走到该点的最优时间
int dir[4][2]={-1,0,1,0,0,-1,0,1};
char map[210][210];
struct node{
      int x,y,time;
};
struct node queue[500001];
void bfs(struct node start)
{
      struct node cur,next;
      int head,tail,i;
      head=tail=0;
      queue[tail++]=start;
      while(head<tail)
      {
             cur=queue[head++];
             for(i=0;i<4;i++)
             {
                    next.x=cur.x+dir[i][0];
                    next.y=cur.y+dir[i][1];
                    if(map[next.x][next.y]=='r'&&mtime>cur.time+1)
                           mtime=cur.time+1;
                    if(next.x>=0&&next.x<n&&next.y>=0&&next.y<m&&map[next.x][next.y]!='#')
                    {
                           if(num[next.x][next.y]>cur.time+1)
                           {
                                  num[next.x][next.y]=cur.time;
                                  next.time=cur.time+1;
                                  if(map[next.x][next.y]=='x')
                                         next.time++;
                                  queue[tail++]=next;
                           }
                    }
             }
      }
}
 
 
int main()
{
      int i,j;
      struct node start;
      while(scanf("%d%d",&n,&m)!=EOF)
      {
             for(i=0;i<n;i++)
             {
                    scanf("%s",map[i]);
                    for(j=0;j<m;j++)
                    {
                           num[i][j]=100000;
                           if(map[i][j]=='a')
                           {
                                  x1=i;
                                  y1=j;
                           }
                    }
             }
             start.x=x1;
             start.y=y1;
             start.time=0;
             mtime=100000;
             bfs(start);
             if(mtime==100000)
                    puts("Poor ANGEL has to stay in the prison all his life.");
             else
                    printf("%d\n",mtime);
      }
      return 0;
}
 
 

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