Solution to the 3rd EulerProj problem

euler3.cpp

// euler3.cpp
// juanfc 2012-06-24
// The prime factors of 13195 are 5, 7, 13 and 29.
// What is the largest prime factor of the number 600851475143 ?

#include <iostream>
using namespace std;

int main()
{
    typedef long long int Tlli;
    Tlli prime = 0;
    Tlli a = 600851475143LL; // a long long constant

    for (Tlli i = 3; i <= a; i += 2) { // even number are not prime
        if (a % i == 0)
            // this avoids composite numbers divide what remains
            a /= (prime = i);

    cout << prime << endl;
    return 0;
}