dfs hdu 1242

http://acm.hdu.edu.cn/showproblem.php?pid=1242

#include<stdio.h>
//DFS ，再次体会对于搜索的优化，array mins[i][j]，保存当前搜到
//maze[i][j]的最优值，
char maze[202][202];
int  vis[202][202],mins[202][202];
int m,n,next[4][2]={1,0,0,1,-1,0,0,-1};
int x,y,xx,yy;
int best=50000,spend;
void dfs(int x,int y)
{
    int t,i,a,b;
    if(x==xx&&y==yy)
    {
        best=spend;
        return ;
    }
    for(i=0;i<4;++i)
    {
        a=x+next[i][0];
        b=y+next[i][1];
        if(!vis[a][b]&&a>=0&&a<m&&b>=0&&b<n&&maze[a][b]!='#')
        {
            if(maze[a][b]=='.')
                t=1;
            else
                t=2;
            spend+=t;
            if(spend<best&&(mins[a][b]==-1||spend<=mins[a][b]))
            {
                mins[a][b]=spend;
                vis[a][b]=1;
                dfs(a,b);
                vis[a][b]=0;
            }
            spend-=t;
        }
    }
}
int main()
{
    int i,j;
    while(scanf("%d%d",&m,&n)==2)
    {
        spend=0;
        best=50000;
        for(i=0;i<m;++i)
        {
            scanf("%s",maze[i]);
            for(j=0;j<n;++j)
            {
                mins[i][j]=-1;
                vis[i][j]=0;
                if(maze[i][j]=='r')
                {
                    x=i;
                    y=j;
                    vis[i][j]=1;
                    maze[i][j]='.';
                }
                else if(maze[i][j]=='a')
                {
                    xx=i;
                    yy=j;
                    maze[i][j]='.';
                }
            }

        }
        dfs(x,y);
        if(best==50000)
            printf("Poor ANGEL has to stay in the prison all his life.\n");
        else
            printf("%d\n",best);

    }

    return 0;
}