【poj 3278】Catch That Cow 题意&题解&代码（C++）

#include<iostream>
#include<algorithm>
#include<stdio.h>
#include<string.h>
#include<queue>
using namespace std;
int n,k,dis[200005];
queue<int>q;
int main()
{
scanf("%d%d",&n,&k);
q.push(n);
memset(dis,-1,sizeof(dis));
int flag=0;
dis
=0;
while(!q.empty()&&flag==0)
{
int now=q.front();q.pop();
if (now<=k && dis[now+1]==-1)
{
dis[now+1]=dis[now]+1;
if (now+1==k)
flag=1;
q.push(now+1);
}
if (now-1>=0 && dis[now-1]==-1)
{
dis[now-1]=dis[now]+1;
if (now-1==k)
flag=1;
q.push(now-1);
}
if (now*2<=k*2 && dis[now*2]==-1)
{
dis[now*2]=dis[now]+1;
if (now*2==k) flag=1;
q.push(now*2);
}
}
printf("%d\n",dis[k]);
}