POJ 3278 Catch That Cow

#include<iostream>#include<cstdio>#include<cstring>#include<algorithm>#include<queue>const int maxn=200000+10;int f[maxn],vis[maxn];using namespace std;int main(){    memset(f,0,sizeof(f));    int n,k,ans,i,j,h;    scanf("%d%d",&n,&k);    queue<int> q;    while(!q.empty()) q.pop();    q.push(n);    while(!q.empty())    {        ans=q.front();        if(ans==k) {printf("%d\n",f[ans]);break;}        i=ans-1;        if(!vis[i]&&i>=0&&i<=100000){            vis[i]=1;            f[i]=f[ans]+1;            q.push(i);}        j=ans+1;        if(!vis[j]&&j>=0&&j<=100000){            vis[j]=1;            f[j]=f[ans]+1;            q.push(j);}        h=ans*2;        if(!vis[h]&&h>=0&&h<=100000){            vis[h]=1;            f[h]=f[ans]+1;            q.push(h);}        q.pop();    }    return 0;}