/// <summary>Returns the sequence of "crossed out" people.</summary>
/// <param name="n">The number of people.</param>
/// <param name="k">The index of crossed out man.</param>
/// <returns></returns>
/// <exception cref="System.ArgumentException">Throws when n or k is negative or equal to zero.</exception>
public static IEnumerable <int> ReturnSequence(int n, int k)
{
if (k <= 0)
{
throw new ArgumentException($"{nameof(k)} is negative or equal to zero.");
}
if (n <= 0)
{
throw new ArgumentException($"{nameof(n)} is negative or equal to zero.");
}
IEnumerable <int> Execute()
{
if (n == 1)
{
yield return(n);
yield break;
}
FlaviusJosephusCollection collection = new FlaviusJosephusCollection(n);
int localK = k;
int localN = 0;
int[] arr;
int arrayToRemoveSize = 0;
if (n > k)
{
arr = new int[n / k];
}
else
{
arr = new int[1];
}
for (int i = 1; i <= n; i++)
{
collection.Add(i);
}
foreach (var element in collection)
{
localK--;
localN++;
if (localK == 0)
{
localK = k;
arr[arrayToRemoveSize] = element;
arrayToRemoveSize++;
}
if (localN == n)
{
for (int i = 0; i < arrayToRemoveSize; i++)
{
collection.Remove(arr[i]);
yield return(arr[i]);
}
localN = 0;
n = collection.CurrentSize;
arrayToRemoveSize = 0;
}
}
yield return(collection[0]);
}
return(Execute());
}
/// <summary>Initializes a new instance of the <see cref="FlaviusJosephusEnumerator"/> class.</summary>
/// <param name="collection">The collection.</param>
public FlaviusJosephusEnumerator(FlaviusJosephusCollection collection)
{
this.flaviusJosephusCollection = collection;
this.position = -1;
}
