/// <summary>
/// Creates the specified number set.
/// </summary>
/// <param name="numberSet">The number set.</param>
/// <returns></returns>
public static IEnumerable <int[]> New(int[] numberSet)
{
var permutationEnumerator = PermutationEnumerator.Create(numberSet.Length).GetEnumerator();
while (permutationEnumerator.MoveNext())
{
var permutation = permutationEnumerator.Current;
var result = new int[numberSet.Length];
for (var i = 0; i < numberSet.Length; i++)
{
result[i] = numberSet[permutation[i]];
}
yield return(result);
}
}
protected internal static IEnumerable <int[]> CreateInternal(int[] numberSet)
{
for (var shiftCount = 0; shiftCount < numberSet.Length; shiftCount++)
{
int[] result = new int[numberSet.Length];
int count = shiftCount;
for (int i = 0; i < numberSet.Length; i++)
{
int index = count + i;
if (index >= numberSet.Length)
{
index -= numberSet.Length;
}
result[i] = numberSet[index];
}
yield return(result);
}
// Initialize the permutation
// simply always make 4 buckets
var buckets = new Dictionary <int, List <int> >();
for (int i = 0; i < numberSet.Length; i++)
{
int bucketNum = i % 4;
List <int> bucket = buckets.Get(bucketNum);
if (bucket == null)
{
bucket = new List <int>();
buckets[bucketNum] = bucket;
}
bucket.Add(numberSet[i]);
}
var permutationEnumerator = PermutationEnumerator.Create(4).GetEnumerator();
// we throw the first one away, it is the same as a shift result
permutationEnumerator.MoveNext();
while (permutationEnumerator.MoveNext())
{
yield return(Translate(numberSet, buckets, permutationEnumerator.Current));
}
}
private void TryPermutation(
int numElements,
int[][] expectedValues)
{
/*
* Total: 4 * 3 * 2 = 24 = 6! (6 faculty)
*
* Example:8
* n / 6 = first number == index 1, total {1}, remains {0, 2, 3}
* remainder 8 - 1 * 6 == 2
* n / 2 = second number == index 1, total {1, 2}, remain {0, 3}
* remainder 2 - 1 * 2 == 0
* == total {1, 2, 0, 3}
*
* Example:21 out {0, 1, 2, 3}
* 21 / 6 == index 3 -> in {3}, out {0, 1, 2}
* remainder 21 - 3 * 6 == 3
* 3 / 2 = second number == index 1 -> in {3, 1}, remain {0, 2}
* remainder 3 - 1 * 2 == 1
* == index 1 -> in {3, 1, 2} out {0}
*/
var enumeration = PermutationEnumerator.Create(numElements).GetEnumerator();
int count = 0;
while (enumeration.MoveNext())
{
int[] result = enumeration.Current;
int[] expected = expectedValues[count];
Log.Debug(".tryPermutation result=" + CompatExtensions.RenderAny(result));
Log.Debug(".tryPermutation expected=" + CompatExtensions.RenderAny(result));
count++;
Assert.IsTrue(Arrays.AreEqual(result, expected),
"Mismatch in count=" + count);
}
Assert.AreEqual(count, expectedValues.Length);
Assert.That(enumeration.MoveNext(), Is.False);
}
public void TestInvalid()
{
Assert.That(() => PermutationEnumerator.Create(0), Throws.ArgumentException);
}