Tempter of the Bone 奇偶剪枝(深搜)

#include <stdio.h>#include <string.h>#include <math.h>#include <stdlib.h>#include <iostream> #include <algorithm>  bool visit[8][8];char map[8][8];int dx[4]={-1,0,1,0};int dy[4]={0,1,0,-1};int Time,row,col,flag,sx,sy,ex,ey;void dfs(int x,int y,int step){     int tx,ty,Min,tstep;     if(map[x][y]=='X')       return ;     if(flag)       return ;     if(x==ex&&y==ey&&step==Time)       {flag=1;return;}     if(step>=Time)        return ;     Min=(int)(fabs((double)(x-ex))+fabs((double)(y-ey)));     if(Min>Time-step)        return ;     if(Min%2!=(Time-step)%2)return;     if(map[ex+1][ey]!='.'&&map[ex-1][ey]!='.'&&map[ex][ey+1]!='.'&&map[ex][ey-1]!='.')return;     for(int i=0;i<4;i++)     {        tx=x+dx[i];        ty=y+dy[i];        tstep=step+1;        if(tx<0||tx>=row||ty<0||ty>=col) continue ;        if(!visit[tx][ty])        {           visit[tx][ty]=true;          dfs(tx,ty,tstep);            visit[tx][ty]=false;           if(flag)return;        }     }          }int main(){      freopen("in.txt","r",stdin);    freopen("out.txt","w",stdout);    int i,j,op,num;    while(scanf("%d %d %d",&row,&col,&Time)==3)    {       if(row+col+Time==0)         break;         num=0;         memset(visit,false,sizeof(visit));       for(i=0;i<row;i++)       {              getchar();                   for(j=0;j<col;j++)        {          scanf("%c",&map[i][j]);          if(map[i][j]=='S'){ sx=i; sy=j;}          else if(map[i][j]=='D') { ex=i; ey=j;}           else num++;        }               }        getchar();           if(num<Time-1||abs(sx-ex)+abs(sy-ey)>Time||( sx + sy + ex + ey +Time )%2==1)       {          printf("NO\n");          continue;       }      /* for(i=0;i<row;i++)       {               for(j=0;j<col;j++)        {          printf("%c",map[i][j]);                   }         printf("\n");       }       */       flag=0;       visit[sx][sy]=true;       dfs(sx,sy,0);       if(flag)          printf("YES\n");       else          printf("NO\n");                            }      return 0;}