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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. #define fast ios::sync_with_stdio(false); cin.tie(nullptr);
  5. #define ll long long
  6. #define endl '\n'
  7. #define all(v) (v).begin(), (v).end()
  8. #define rall(v) (v).rbegin(), (v).rend()
  9.  
  10. const int oo = 1e9;
  11. const ll INF = 1e18;
  12. const ll MOD = 1e9+7;
  13.  
  14. void solve(){
  15.     ll n; cin >> n;
  16.     ll ans = 0;
  17.     ll l=1 , r=1;
  18.     while(l<n){
  19.         ll q = n/l;
  20.         r = min(n/q , n);
  21.         ll sum = (r-l+1)*(r+l)/2;
  22.         ans = ( ans % MOD + (sum % MOD * q % MOD) % MOD ) %MOD;
  23.         l = r + 1;
  24.     }
  25.     cout<<ans;
  26. }
  27.  
  28. int main()
  29. {
  30.     fast
  31.  
  32.     int t = 1;
  33.     // cin >> t;
  34.  
  35.     while (t--)
  36.         solve();
  37.  
  38.     return 0;
  39. }
Success #stdin #stdout 0.56s 5328KB
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-652367001
https://ideone.com/sa9rUF
language:
C++ (gcc 8.3)
created:
2 days ago
visibility:
public

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