private static void ThreeWaySort <T>(IList <T> collection, int lo, int hi, IComparer <T> comparer)
{
if (hi <= lo)
{
return;
}
int lt = lo;
int i = lo + 1;
int gt = hi;
var v = collection[lo];
while (i <= gt)
{
int cmp = comparer.Compare(collection[i], v);
if (cmp < 0)
{
SortingBase.Exch(collection, lt++, i++);
}
else if (cmp > 0)
{
SortingBase.Exch(collection, i, gt--);
}
else
{
i++;
}
}
Sort(collection, lo, lt - 1, comparer);
Sort(collection, gt + 1, hi, comparer);
}
private static int Partition <T>(IList <T> collection, int lo, int hi, IComparer <T> comparer)
{
int i = lo;
int j = hi + 1;
var v = collection[lo];
while (true)
{
while (SortingBase.Less(collection[++i], v, comparer))
{
if (i == hi)
{
break;
}
}
while (SortingBase.Less(v, collection[--j], comparer))
{
if (j == lo)
{
break;
}
}
if (i >= j)
{
break;
}
SortingBase.Exch(collection, i, j);
}
SortingBase.Exch(collection, lo, j);
return(j);
}
private static void Merge <T>(IList <T> collection, int lo, int mid, int hi, T[] aux, IComparer <T> comparer)
{
Debug.Assert(IsSorted(collection, lo, mid, comparer));
Debug.Assert(IsSorted(collection, mid + 1, hi, comparer));
int i = lo;
int j = mid + 1;
for (int k = lo; k <= hi; k++)
{
aux[k] = collection[k];
}
for (int k = lo; k <= hi; k++)
{
if (i > mid)
{
collection[k] = aux[j++];
}
else if (j > hi)
{
collection[k] = aux[i++];
}
else if (SortingBase.Less(aux[j], aux[i], comparer))
{
collection[k] = aux[j++];
}
else
{
collection[k] = aux[i++];
}
}
}
private static bool IsSorted <T>(IList <T> collection, int lo, int hi, IComparer <T> comparer)
{
for (int i = lo + 1; i <= hi; i++)
{
if (SortingBase.Less(collection[i], collection[i - 1], comparer))
{
return(false);
}
}
return(true);
}
/// <summary>
/// Sort the List
/// </summary>
/// <typeparam name="T">the type of the stored values</typeparam>
/// <param name="collection">the collection to sort</param>
/// <param name="comparer">the comparer for the values, if not specified the default comparer is used</param>
public static void InsertionSort <T>(this IList <T> collection, IComparer <T> comparer = null)
{
comparer ??= Comparer <T> .Default;
int n = collection.Count;
for (int i = 1; i < n; i++)
{
for (int j = i; j > 0 && SortingBase.Less((T)collection[j], (T)collection[j - 1], comparer); j--)
{
SortingBase.Exch(collection, j, j - 1);
}
}
}
/// <summary>
/// Sort the List
/// </summary>
/// <typeparam name="T">the type of the stored values</typeparam>
/// <param name="collection">the collection to sort</param>
/// <param name="comparer">the comparer for the values, if not specified the default comparer is used</param>
public static void SelectionSort <T>(this IList <T> collection, IComparer <T> comparer = null)
{
comparer ??= Comparer <T> .Default;
int n = collection.Count;
for (int i = 0; i < n; i++)
{
int min = i;
for (int j = i + 1; j < n; j++)
{
if (SortingBase.Less(collection[j], collection[min], comparer))
{
min = j;
}
}
SortingBase.Exch(collection, i, min);
}
}
/// <summary>
/// Sort the List
/// </summary>
/// <typeparam name="T">the type of the stored values</typeparam>
/// <param name="collection">the collection to sort</param>
/// <param name="comparer">the comparer for the values, if not specified the default comparer is used</param>
public static void ShellSort <T>(this IList <T> collection, IComparer <T> comparer = null)
{
comparer ??= Comparer <T> .Default;
int n = collection.Count;
int h = 1;
while (h < n / 3)
{
h = 3 * h + 1;
}
while (h >= 1)
{
for (int i = h; i < n; i++)
{
for (int j = i; j >= h && SortingBase.Less((T)collection[j], (T)collection[j - h], comparer); j -= h)
{
SortingBase.Exch(collection, j, j - h);
}
}
h /= 3;
}
}
