/// <summary>
/// Finds sum of all primes below n
/// </summary>
/// <param name="n"></param>
/// <returns></returns>
public static long Problem10(long n)
{
long Sum = 0;
for (int i = 1; i <= n; i++)
{
if (MathsFunctions.IsPrime(i))
{
Sum += i;
}
}
long Correction = Sum - 1;
return(Correction);
}
/// <summary>
/// Finds the largest prime divisor of n
/// </summary>
/// <param name="n">works for values of i*i < n</param>
/// <returns>returns largest value</returns>
public static long Problem3(long n = 600851475143)
{
long div = 1;
for (long i = 1; i *i <= n; i++)
{
if (n % i == 0)
{
if (MathsFunctions.IsPrime(i))
{
div = i;
}
}
}
return(div);
}
/// <summary>
/// Finds the nth prime number by iteratively adding primes to a list, then returns the last value on the list
/// </summary>
/// <param name="n">nth prime</param>
/// <returns></returns>
public static long Problem7(int n)
{
List <long> PrimeList = new List <long>();
for (int i = 2; i < n * n; i++)
{
if (MathsFunctions.IsPrime(i))
{
PrimeList.Add(i);
long[] Primes = PrimeList.ToArray();
if (Primes.Length == n)
{
break;
}
}
}
return(PrimeList.Last());
}
/// <summary>
/// Finds the largest palindrome for 2 n digits values multiplied together
/// </summary>
/// <param name="n"></param>
/// <returns></returns>
public static int Problem4(int n = 3)
{
int Largest = 0;
for (int i = 10 ^ (n - 1); i < Math.Pow(10, n); i++)
{
for (int j = 10 ^ (n - 1); j < Math.Pow(10, n); j++)
{
int t = i * j;
if (MathsFunctions.IsPalindrome(t))
{
if (t > Largest)
{
Largest = t;
}
}
}
}
return(Largest);
}