hdu 1010

经典的深搜 

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

#include<stdio.h>
#include<stdlib.h>
char map[10][10];
int n,m,t;
int sx,sy,dx,dy;
int found;
int dir[4][2]={{-1,0},{1,0},{0,1},{0,-1}};
void dfs(int x,int y,int k)
{
    if(t==k&&dx==x&&dy==y)
        found=1;
    if(found)
        return;

    int v=t-k-abs(dx-x)-abs(dy-y);
    if(v<0||v&1)
        return;

    for(int i=0;i<4;i++)
    {
        int xx=dir[i][0]+x;
        int yy=dir[i][1]+y;
        if(xx>=0&&xx<n&&yy>=0&&yy<m&&map[xx][yy]!='X')
        {
            map[xx][yy]='X';
            dfs(xx,yy,k+1);
            map[xx][yy]='.';
        }
    }
}

int main()
{
    while(scanf("%d %d %d",&n,&m,&t))
    {
        
        if(n==0&&m==0&&t==0)
            break;
        int remain=0;
        found=0;
        int i,j;
        getchar();
        for(i=0;i<n;i++)
        {
            for(j=0;j<m;j++)
            {
                scanf("%c",&map[i][j]);
                if(map[i][j]=='S')
                {
                    sx=i;
                    sy=j;
                }
                else if(map[i][j]=='D')
                {
                    dx=i;
                    dy=j;
                    remain++;
                }
                else if(map[i][j]=='.')
                    remain++;
            }
            getchar();
        }
        
        map[sx][sy]='X';
        if(remain>=t)
            dfs(sx,sy,0);
        if(found)
            printf("YES\n");
        else
            printf("NO\n");

    }
    return 0;
}