//The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17.
//Find the sum of all the primes below two million.
public static long Execute()
{
const int max = 2000000;
long sum = 0;
for (var i = 2; i < max; i++)
{
if (PrimeHelper.IsPrimeWithHistory(i))
{
sum += i;
}
}
return(sum);
}
//By listing the first six prime numbers: 2, 3, 5, 7, 11, and 13, we can see that the 6th prime is 13.
//What is the 10001st prime number?
/// <summary>
/// 500000 gives 7368787 and takes 5 seconds
/// </summary>
public static int Execute()
{
var maxPrimeCount = 10001;
// Skip first 3 primes
var primeCount = 3;
var i = 3;
while (primeCount <= maxPrimeCount)
{
i = i + 2;
if (PrimeHelper.IsPrimeWithHistory(i))
{
primeCount++;
}
}
return(i);
}