hdu1010 Tempter of the Bone (深搜)

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
char map[10][10];
int T,M,N,sx,sy,ex,ey;
int ans;
int dir[4][2]={-1,0,1,0,0,1,0,-1};
bool Input(){
    scanf("%d%d%d\n",&N,&M,&T);
    if(!N && !M && !T) return false;
    int i,j;
    for(i=1;i<=N;i++){
        gets(map[i]+1);
        for(j=1;j<=M;j++){
            if(map[i][j]=='S'){
                sx=i;
                sy=j;
            }
            else if(map[i][j]=='D'){
                ex=i;
                ey=j;
            }
        }
    }
    return true;
}
void dfs(int x,int y,int k){
    if(ans) return;
    if(k==T){
        if(map[x][y]=='D') ans=1;
        return;
    }
    int i,a,b;
    char ch=map[x][y];
    map[x][y]='X';
    for(i=0;i<4;i++){
        a=x+dir[i][0];
        b=y+dir[i][1];
        if(a>0 && a<=N && b>0 && b<=M && (map[a][b]=='.' || map[a][b]=='D')){
            dfs(a,b,k+1);
        }
    }
    map[x][y]=ch;
}
int main(){
    //freopen("in.txt","r",stdin);
    memset(map,0,sizeof(map));
    while(Input()){
        if((abs(ex-sx)+abs(ey-sy))%2 != T%2){
            puts("NO");
            continue;
        }
        ans=0;
        dfs(sx,sy,0);
        puts(ans?"YES":"NO");
        memset(map,0,sizeof(map));
    }
    return 0;
}