UVa 11395 - Sigma Function

Accepted date: 2015-07-26
Ranking (as of 2015-07-26): 32 out of 228
Language: C++

/*
  UVa 11395 - Sigma Function

  To build using Visual Studio 2012:
    cl -EHsc -O2 UVa_11395_Sigma_Function.cpp
*/

#include <iostream>
#include <cmath>
using namespace std;

/*
Sigma Function of n is odd if and only if n is square or twice square.
*/

int main()
{
  while (true) {
    long long N;
    cin >> N;
    if (!N)
      break;
    int i = static_cast<int>(sqrt(static_cast<double>(N))),
      j = static_cast<int>(sqrt(static_cast<double>(N / 2)));
    cout << N - (i + j) << endl;
  }
  return 0;
}