/// <summary>
/// https://projecteuler.net/problem=68
/// </summary>
/// <param name="arguments"></param>
/// <returns></returns>
public static Result Magic5GonRing(Problem arguments)
{
var n = arguments.ListOfNumbers;
var ringSize = arguments.IntNumber;
var sideLength = 3;
var ring = UtilityMath.GetPentagonalRing(n, sideLength, ringSize);
// traverse ring in circular index from smaller outer node
// if iendex go: n, 0, 1,..., n-2, n-1
var index = new int[ringSize];
var v = 0;
index[0] = ringSize - 1;
for (var i = 1; i < ringSize; i++)
{
index[i] = v;
v++;
}
var builder = new StringBuilder();
foreach (var i in index)
{
var side = ring[i];
foreach (var d in side)
{
builder.Append(d.ToString());
}
}
string answer = builder.ToString();
var message = string.Format("The maximum 16-digit string for a \"magic\" 5-gon ring is {0}.", answer);
if (Answers[arguments.Id] != answer)
{
message += string.Format(" => INCORRECT ({0})", Answers[arguments.Id]);
}
var r = new Result(arguments.Id, message)
{
Answer = answer
};
return(r);
}