UVa/11526 - H(n)/11526.cpp

   1 #include <iostream>
   2 #include <cstdio>
   3 using namespace std;
   4
   5 long long n;
   6 int main(){
   7     int t; cin >> t;
   8     while (t-- && cin >> n){
   9         if (n <= 0){ cout << "0" << endl; continue; }
  10
  11         long long res = 0;
  12         long long i = 1;
  13         while (i <= n){
  14             long long start = n / i;
  15             long long low = i, high = n;
  16             while (low < high){
  17                 //long long mid = (low + high + 1) / 2;//low + (high - low + 1) / 2;
  18                 long long mid = low + (high - low + 1) / 2;
  19                 //printf("low=%lld, high=%lld, mid=%lld, i=%lld\n", low, high, mid, i);
  20                 if (n / mid != start) high = mid - 1;
  21                 else low = mid;
  22             }
  23             res += (low - i + 1) * start;
  24             i = low + 1;
  25         }
  26         cout << res << endl;
  27     }
  28     return 0;
  29 }