/// <inheritdoc cref="Compare"/>
public int compare(int[] c1, int[] c2)
{
if (c1.Length != k)
{
throw new DimensionMismatchException(c1.Length, k);
}
if (c2.Length != k)
{
throw new DimensionMismatchException(c2.Length, k);
}
// Method "lexNorm" works with ordered arrays.
int[] c1s = MathArrays.copyOf(c1);
Array.Sort(c1s);
int[] c2s = MathArrays.copyOf(c2);
Array.Sort(c2s);
long v1 = lexNorm(c1s);
long v2 = lexNorm(c2s);
if (v1 < v2)
{
return(-1);
}
else if (v1 > v2)
{
return(1);
}
else
{
return(0);
}
}
/// <inheritdoc/>
/// <remarks>
/// This method calls <see cref="MathArrays.shuffle(int[],RandomGenerator)"/>
/// in order to create a random shuffle of the set
/// of natural numbers <c>{ 0, 1, ..., n - 1 </c>}.
/// </remarks>
/// <exception cref="NumberIsTooLargeException"> if <c>k > n</c>.</exception>
/// <exception cref="NotStrictlyPositiveException"> if <c>k <= 0</c>.</exception>
public int[] nextPermutation(int n, int k)
{
if (k > n)
{
throw new NumberIsTooLargeException <Int32, Int32>(new LocalizedFormats("PERMUTATION_EXCEEDS_N"), k, n, true);
}
if (k <= 0)
{
throw new NotStrictlyPositiveException <Int32>(new LocalizedFormats("PERMUTATION_SIZE"), k);
}
int[] index = MathArrays.natural(n);
MathArrays.shuffle(index, getRandomGenerator());
// Return a new array containing the first "k" entries of "index".
return(MathArrays.copyOf(index, k));
}