light oj 1098 数学规律

 #include <stdio.h>
 #include <string.h>
 #include <stdlib.h>
 #include <math.h>
 #include <iostream>
 #include <algorithm>
 #include <climits>
 #include <queue>
 #define ll long long

 using namespace std;

 const ll MAX = (ll)sqrt(2e9)+;
 const ll MOD = 1e9+;

 ll ok(ll a1, ll an, ll d)
 {
     return ((an-a1)/d+)*(a1+an)/;
 }

 void solve()
 {
     ll n,k;
     ll sum = ;
     scanf("%lld",&n);
     k = (ll)sqrt(n);

     for(ll i = ; i <= k; i++)
     {
         sum += i*(n/i-);
         if(i < n/i)
             sum += (i-) * ok(n/(i+)+, n/i, );
     }

     printf("%lld\n",sum);
 }
 int  main(void)
 {

     ll t,cnt = ;
     scanf("%lld",&t);
     while(t--)
     {
         printf("Case %lld: ",++cnt);
         solve();
     }
     return ;
 }