hoj-1010 Tempter of the Bone

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
using namespace std;
int n,m,t,p,ex,ey;
char map[10][10];
int yi[4][2]={{1,0},{-1,0},{0,1},{0,-1}};
void dfs(int x,int y,int time)
{
    if (x<1||x>n||y<1||y>m||time>t||p==1) return ;
    int a=abs(x-ex);
    int b=abs(y-ey);
      a+=b;
    if (a>t-time) return ;
    if (x==ex&&y==ey&&time==t)
    {
         p=1;
        return ;
    }
    for (int i=0;i<4;i++)
    {
        int rx=x+yi[i][0];
        int ry=y+yi[i][1];
        if (map[rx][ry]!=‘X‘)
        {
            map[rx][ry]=‘X‘;
            dfs(rx,ry,time+1);
            map[rx][ry]=‘.‘;
        }
    }
    return ;
}
int main()
{
    int i,j,x,y,z,a,b;
    while (~scanf("%d%d%d",&n,&m,&t))
    {
        z=0;
        if (n==0&&m==0&&t==0) break;
        p=0;
        for (i=1;i<=n;i++)
        for (j=1;j<=m;j++)
        {
            scanf(" %c",&map[i][j]);
            if (map[i][j]==‘S‘){x=i;y=j;}
            if (map[i][j]==‘X‘) z++;
            if (map[i][j]==‘D‘) {ex=i;ey=j;}
        }
         a=abs(x-ex);
     b=abs(y-ey);
    a+=b;
        if (m*n-z<=t||a%2!=t%2||a>t)
        {
            printf("NO\n");
            continue;
        }
        map[x][y]=‘X‘;
        dfs(x,y,0);
        if (p==0) printf("NO\n");
        else printf("YES\n");
    }
    return 0;
}