public void Problem3Test()
{
var p3 = new Problem3();
List <long> res = p3.FindPrimes(13195 / 2);
res = p3.FindFactors(res, 13195);
var largestPrimeFactor = res[res.Count - 1];
Assert.AreEqual(largestPrimeFactor, 29);
//heuristics - 600851475143/2 is even hence 300425737572 non-prime
//sqrt ()= 775146
//var val = BigInteger.Pow (600851475143, 1/2).ToString((type)BigInteger);
res = p3.FindPrimes(775147);
res = p3.FindFactors(res, 600851475143);
largestPrimeFactor = res[res.Count - 1];
Assert.AreEqual(largestPrimeFactor, 6857);
}