hdu2717Catch That Cow 简单BFS

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=2717

刚开始思路错了，用的DP，一直WA,后来才发现是搜索，还是简单的BFS，顿时。。。。

思路：

BFS 三个方向即可；

代码：

#include<iostream>
#include<cstdlib>
#include<cstdio>
#include<cmath>
#include<cstring>
#include<fstream>
#include<queue>
#define MAX 100010
using namespace std;
int n,k;
int  cur,next;
int step[MAX];
queue<int>q;
void bfs()
{
        while(!q.empty())
        {
              cur=q.front();
              q.pop();
              if(cur==k)  break;
              next=cur-1;
              if(next>=0&&step[next]==0)
              {
                      q.push(next);
                      step[next]=step[cur]+1;
              }
              next=cur+1;
              if(step[next]==0)
              {
                      q.push(next);
                      step[next]=step[cur]+1;
              }
              next=cur*2;
              if(next<=100000&&(next-k)<(k-cur)&&step[next]==0)
              {
                      q.push(next);
                      step[next]=step[cur]+1;
              }
        }

}
int main()
{
       while(scanf("%d%d",&n,&k)!=EOF)
       {
              memset(step,0,sizeof(step));
              if(n>k)
                      cout<<(n-k)<<endl;
               else
                   {
                        while(!q.empty()) q.pop();
                        q.push(n);
                        bfs();
                        cout<<step[k]<<endl;
                   }
       }
       return 0;
}