/// <summary>
/// Testing the method <see cref="PermutationGenerator.Subset"/>.
/// </summary>
[Test] public void Subset()
{
int[] array = new int[100];
for (int i = 0; i < array.Length; i++)
{
array[i] = i;
}
// testing 30 < 100 / 2
ICollection subset = PermutationGenerator.Subset(array, 30);
int lastItem = -1;
foreach (int item in subset)
{
Assertion.Assert("#A00 The order of the elements is not preserved.",
item > lastItem);
lastItem = item;
}
// testing 60 > 100 / 2
subset = PermutationGenerator.Subset(array, 60);
lastItem = -1;
foreach (int item in subset)
{
Assertion.Assert("#A00 The order of the elements is not preserved.",
item > lastItem);
lastItem = item;
}
}
/// <summary>
/// Gets an array of <c>k</c> indices picked uniformly drawn from the
/// interval <c>[0, n-1]</c>.
/// </summary>
public static int[] Next(int n, int k)
{
if (n < 0 || k < 0)
{
throw new ArgumentException(
"#E00 n and k must be non negative integer.");
}
if (k > n)
{
throw new ArgumentException(
"#E01 n must be greater or equal to k.");
}
/* Current implementation relies of the permutation generator and
* therefore requires a O(n*log(n)) computation time to run.
*
* This complexity could be significantly improved, especially for
* small k. */
int[] permutation = PermutationGenerator.Next(n);
int[] combination = new int[k];
for (int i = 0; i < k; i++)
{
combination[i] = permutation[i];
}
return(combination);
}
/// <summary>
/// Testing the method <see cref="PermutationGenerator.Shuffle"/>.
/// </summary>
[Test] public void Suffle()
{
int[] array = new int[100];
for (int i = 0; i < array.Length; i++)
{
array[i] = i;
}
PermutationGenerator.Shuffle(array);
Array.Sort(array);
for (int i = 0; i < array.Length; i++)
{
Assertion.AssertEquals("#A00 Unexpected array value", i, array[i]);
}
}
