zoj 2527 Series

#include <iostream>#include <stdio.h>#include <algorithm>using namespace std;long long int n,a[1010],ans=-1,tot;int main(){int i,j,k,tmp;while (cin>>n){ans=-1;for (i=1; i<=n; i++) cin>>a[i];sort(a+1,a+n+1);for (i=1; i<=n; i++){for (j=i+1; j<=n; j++){tot=2;tmp=a[j]-a[i]+a[j];for (k=j+1; k<=n; k++){if (a[k]>tmp) break;if (a[k]==tmp){tot++;tmp=a[k]+a[j]-a[i];}}ans=max(ans,tot);}}cout<<ans<<endl;}return 0;}