bzoj1257

一段一段。。

 1 #include<cstdio>
 2 #include<cstring>
 3 #include<ctime>
 4 #include<cmath>
 5 #include<algorithm>
 6 #include<cstdlib>
 7 #include<iostream>
 8 #define rep(i,l,r) for(int i=l;i<r;i++)
 9 typedef long long ll;
10 using namespace std;
11 int n,k;
12 ll ans=0;
13 int main(){
14     scanf("%d%d",&n,&k);
15     if(n>=k){
16         ans=ll(k)*ll(n-k);
17         n=k-1;
18     }
19     for(int l=1;l<=n;l++){
20         int t=k/l,r=k/t;
21         if(r>n) r=n;
22         ans+=ll(k)*ll(r-l+1)-ll(t)*ll(l+r)*ll(r-l+1)/2;
23         l=r;
24     }
25     printf("