Project Euler Forum

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snip

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long n = 600851475143L;

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#include <stdio.h>
#include <math.h>

int main()
{
   long long n = 600851475143ll; // have also tried with LL
   long long o = sqrt(n);

   printf("%d\n", n);
   printf("%d\n", o);

   return 0;
}

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printf("%lld\n", n);

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#include <iostream>
using namespace std;
#include <iomanip>
using namespace std;
#include <vector>
using namespace std;
#include <math.h>
using namespace std; 


// This program will take a number and find its divisors, then store them in an doubleerger vector.

void findPrimeDivisors(double, double, vector<double> &);
bool isPrime (double);

void main()
{

  double number;
  double vectorindex = 0;
  vector <double> divisors;
  vector <double> primes;
  


  cout << "Please enter the number for which you would like to find the divisors: " << endl;
  cin >> number;
  cout << "The primefactors for " << number <<" are: " ;
  findPrimeDivisors (number, vectorindex, divisors);
  cout<< endl;
  
  cin >> number; //Delay program exit
}

void findPrimeDivisors(double num, double index,  vector<double> &integers)
{
  for(double counter = 1; counter <= num; counter ++)
  {
       
    if ( (int)num % (int)counter == 0) // Checking if 'counter' is a divisor of 'number'
      {
		 if ( isPrime(counter) )       // If it's a divisor, checking if it's prime.
         {
		 integers.push_back(counter);
         cout << integers[index] << " ";
         index ++;   
		 }
      }
	
  }   
}

 bool isPrime (double num)
{

	if (num <=1)
		return false;
	else if (num == 2)         
		return true;
	else if ((int)num % 2 == 0)
		return false;
	else
	{
		bool prime = true;
		double divisor = 3;
		double num_d = static_cast<double>(num);
		double upperLimit = static_cast<double>(sqrt(num_d) +1);
        
		while (divisor <= upperLimit)
		{
			if ((int)num % (int)divisor == 0)
				prime = false;
			divisor +=2;
		}
		return prime;
	}
}