#include<iostream>
#include<cstring>
#include<cstdlib>
#include<cstdio>
#define ll long long
using namespace std;
const int maxn=500010,mod=1e9+7;
int n,k,l,r;
ll sum;
void read(int &k)
{
int f=1;k=0;char c=getchar();
while(c<‘0‘||c>‘9‘)c==‘-‘&&(f=-1),c=getchar();
while(c<=‘9‘&&c>=‘0‘)k=k*10+c-‘0‘,c=getchar();
k*=f;
}
int main()
{
read(n);read(k);
sum=1ll*n*k;n=min(n,k);
for(int i=1;i<=n;i=r+1)
{
int j=k/i;l=k/(j+1)+1;r=k/j;
if(r>=n)r=n;
sum-=1ll*(l+r)*(r-l+1)*j>>1;
}
printf("%lld",sum);
}
来源: http://www.bubuko.com/infodetail-2280261.html