public static long Solution()
{
long solution = 0;
var stopwatch = new Stopwatch();
stopwatch.Start();
var previousTime = 0.0;
var currentTime = 0.0;
var count = 0;
var solutions = new List <long>();
for (int i = 7; count < limit; i++)
{
var order = UtilityFunctions.MultiplicativeOrder(10, 9 * i);
if (order > 0 && (i - 1) % order == 0 && !UtilityFunctions.IsPrime(i))
{
count += 1;
solution += i;
solutions.Add(i);
Console.Write($"{ i}, ");
}
}
currentTime = stopwatch.ElapsedMilliseconds;
Console.WriteLine($"Solution took {currentTime - previousTime} seconds.");
Console.WriteLine(solutions.ToArray());
return(solution);
}
public static long Solution()
{
var stopwatch = new Stopwatch();
stopwatch.Start();
for (int i = upperLimit + 1; true; i += 2)
{
var order = UtilityFunctions.MultiplicativeOrder(10, 9 * i);
if (order > upperLimit)
{
Console.WriteLine($"Solution took {stopwatch.ElapsedMilliseconds} milliseconds.");
return(i);
}
}
}
public static long Solution()
{
long solution = 0;
var primes = UtilityFunctions.Primes(limit);
foreach (var p in primes)
{
var ord = UtilityFunctions.MultiplicativeOrder(10, 9 * p);
if (ord == 0)
{
solution += p;
continue;
}
while (ord % 2 == 0 || ord % 5 == 0)
{
if (ord % 2 == 0)
{
ord /= 2;
}
if (ord % 5 == 0)
{
ord /= 5;
}
}
if (ord > 1)
{
solution += p;
}
else
{
Console.WriteLine(p);
}
}
return(solution);
}
public static long Solution()
{
long solution = 0;
var counter = 0;
var stopwatch = new Stopwatch();
stopwatch.Start();
var previousTime = 0.0;
var currentTime = 0.0;
var primes = UtilityFunctions.Primes(1000000);
currentTime = stopwatch.ElapsedMilliseconds;
Console.WriteLine($"Settig up took {currentTime - previousTime} milliseconds.");
previousTime = currentTime;
foreach (var p in primes)
{
var order = UtilityFunctions.MultiplicativeOrder(10, 9 * p);
if (order == 0)
{
continue;
}
if (limit % order == 0)
{
solution += p;
counter += 1;
Console.WriteLine(p);
if (counter >= 40)
{
return(solution);
}
}
}
return(solution);
}