hdu1010

http://acm.hdu.edu.cn/showproblem.php?pid=1010

Tempter of the Bone

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 89573    Accepted Submission(s): 24362

Problem Description

The doggie found a bone in an ancient maze, which fascinated him a lot. However, when he picked it up, the maze began to shake, and the doggie could feel the ground sinking. He realized that the bone was a trap, and he tried desperately to get out of this maze.

The maze was a rectangle with sizes N by M. There was a door in the maze. At the beginning, the door was closed and it would open at the T-th second for a short period of time (less than 1 second). Therefore the doggie had to arrive at the door on exactly the T-th second. In every second, he could move one block to one of the upper, lower, left and right neighboring blocks. Once he entered a block, the ground of this block would start to sink and disappear in the next second. He could not stay at one block for more than one second, nor could he move into a visited block. Can the poor doggie survive? Please help him.

 

Input

The input consists of multiple test cases. The first line of each test case contains three integers N, M, and T (1 < N, M < 7; 0 < T < 50), which denote the sizes of the maze and the time at which the door will open, respectively. The next N lines give the maze layout, with each line containing M characters. A character is one of the following:

'X': a block of wall, which the doggie cannot enter; 
'S': the start point of the doggie; 
'D': the Door; or
'.': an empty block.

The input is terminated with three 0's. This test case is not to be processed.

 

Output

For each test case, print in one line "YES" if the doggie can survive, or "NO" otherwise.

 

Sample Input

   
   
   
   

    
    
    
    4 4 5
S.X.
..X.
..XD
....
3 4 5
S.X.
..X.
...D
0 0 0
   
   
   
   

 

Sample Output

   
   
   
   

    
    
    
    NO
YES
   
   
   
   

 

有一条狗，在一个迷宫里有一根骨头，这只狗很馋，进入迷宫，叼走了骨头，当他叼走骨头时，他每走一步，走过的路开始开始下陷，狗每走一步用时一秒，他可以选择上下左右走，但是“X"表示墙，不可以过，”D"表示门，问这只狗能不能在t时刻走到门口

#include <iostream>
#include <stdio.h>
#include <math.h>
#include <stdlib.h>
using namespace std;
int sx,sy,gx,gy;
int T,t,flag;
char  map[10][10];
int N,M;
int d[4][2]= { {1,0},{0,1},{0,-1},{-1,0} };
void bfs(int x,int y,int t)
{
    if(flag==1)
        return;
    if(t<abs(x-gx)-abs(y-gy)||(t-abs(x-gx)-abs(y-gy))%2==1)
        return;
    if(t==0)
    {
        if(x==gx&&y==gy)
        {
            flag=1;
            return;
        }
        else
            return;
    }
    for(int i=0; i<4; i++)
    {
        int nx=d[i][0]+x;
        int ny=d[i][1]+y;
        if(nx>=0&&ny>=0&&nx<N&&ny<M&&(map[nx][ny]=='.'||map[nx][ny]=='D'))
        {
            map[nx][ny]='X';
            bfs(nx,ny,t-1);
            map[nx][ny]='.';
        }
    }
    return;

}
int main()
{
    while(~scanf("%d%d%d",&N,&M,&T))
    {
        if(N==0&&M==0&&T==0)
            break;
        for(int i=0; i<N; i++)
        {
            scanf("%s",map[i]);
            for(int j=0; j<M; j++)
            {
                if(map[i][j]=='S')
                {
                    sx=i,sy=j;
                }
                if(map[i][j]=='D')
                {
                    gx=i,gy=j;
                }
            }
        }
        flag=0;
        t=T;
        bfs(sx,sy,t);
        if(flag)
            printf("YES\n");
        else
            printf("NO\n");

    }
    //cout << "Hello world!" << endl;
    return 0;
}