1012 Rescue

Rescue

Time Limit : 2000/1000ms (Java/Other) Memory Limit : 65536/32768K (Java/Other)
Total Submission(s) : 117 Accepted Submission(s) : 35
[align=left]Problem Description[/align]
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.<br><br>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.<br><br>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.)<br>

[align=left]Input[/align]
First line contains two integers stand for N and M.<br><br>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. <br><br>Process to the end of the
file.<br>

[align=left]Output[/align]
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." <br>

[align=left]Sample Input[/align]

7 8<br>#.#####.<br>#.a#..r.<br>#..#x...<br>..#..#.#<br>#...##..<br>.#......<br>........<br>

[align=left]Sample Output[/align]

13<br>
看到第一眼应该是个广搜题，但我还是用深搜做的，并没有什么技术含量代码：#include<stdio.h>
#include<string.h>
int n,m,ok,ans,vis[205][205];
char mat[205][205];
void dfs(int x,int y,int step)
{
    if(vis[x][y] || mat[x][y]=='#' || step>=ans) return;
    if(mat[x][y]=='r')
    {
        ok=1;
        if(step<ans) ans=step;
        return;
    }
    if(mat[x][y]=='x')
        step++;
    vis[x][y]=1;
    dfs(x+1,y,step+1);
    dfs(x-1,y,step+1);
    dfs(x,y+1,step+1);
    dfs(x,y-1,step+1);
    vis[x][y]=0;
}
int main()
{
    while(~scanf("%d %d%*c",&n,&m))
    {
        memset(mat,'#',sizeof(mat));
        int i,j,sti,stj;
        for(i=1; i<=n; i++)
        {
            for(j=1; j<=m; j++)
            {
                scanf("%c",&mat[i][j]);
                if(mat[i][j]=='a')
                {
                    sti=i;
                    stj=j;
                }
            }
            getchar();
        }
        ok=0;
        ans=100000;
        dfs(sti,stj,0);
        if(ok) printf("%d\n",ans);
        else printf("Poor ANGEL has to stay in the prison all his life.\n");
    }
    return 0;