余数之和BZOJ1257

#include <iostream>
#include <cstdio>
#include <cmath>
#include <algorithm>

using namespace std;

typedef long long ll;

ll n,k;
ll sum =0;
int main()
{
    cin >> n >> k;
   for(ll i=1,j;i<=n;i=j+1)
   { 
       ll p = k/i;
       if(p ==0)j=n;
       else j = min(k/p,n);
       ll f= k%i;
       ll t =k%j;
       sum+=(j-i+1)*(f+t)/2;
   }
    cout << sum <<endl;
    return 0;
}