HDU - 2717 Catch That Cow

题目思路：

  bfs的模板题     戳我戳我

题目代码：

#include<iostream>
#include<cstdio>
#include<cstring>
#include<queue>
#include<cmath>
#define maxn 1000000

using namespace std;
int vis[maxn];

struct COO
{
     int pos;
     int tim;
}start,mid,nxt;
queue<COO>q;

int main(void)
{
     int n,k;
     //int flag;
     while(~scanf("%d%d",&n,&k))
     {
          if(n>=k)
          {
               printf("%d\n",n-k);
               continue;
          }
          memset(vis,0,sizeof(vis));
          while(!q.empty())
               q.pop();
          //flag=1;
          //int over=abs(n-k);
          start.pos=n;
          start.tim=0;
          vis[n]=1;
          q.push(start);
          while(!q.empty())
          {
               mid=q.front();
               q.pop();
               if(mid.pos==k)
               {
                    //flag=0;
                    printf("%d\n",mid.tim);
                    break;
               }
               for(int i=0;i<3;i++)
               {
                    int nx;
                    switch(i)
                    {
                         case 0:nx=mid.pos-1;break;
                         case 1:nx=mid.pos+1;break;
                         case 2:nx=mid.pos*2;break;
                    }
                    if(nx<maxn&&nx>=0&&!vis[nx])
                    {
                         nxt.pos=nx;
                         nxt.tim=mid.tim+1;
                         vis[nx]=1;
                         q.push(nxt);
                    }
               }
          }
     }
     return 0;
}

呼呼