public static void QuickSort <T>(this IList <T> items)
where T : IComparable <T>
{
var stats = new SortStats();
QuickSort(items, 0, items.Count - 1, stats);
Console.WriteLine("QuickSort: {0}", stats);
}
public static void MergeSortInPlace <T>(IList <T> input)
where T : IComparable <T>
{
SortStats ss = new SortStats();
T[] scratch = new T[input.Count];
MergeSortInPlace(input, 0, input.Count - 1, ss, scratch);
Console.WriteLine("Mergesort: {0}", ss);
}
static void QuickSort <T>(IList <T> A, int p, int r, SortStats ss)
where T : IComparable <T>
{
if (p < r)
{
int q = Partition(A, p, r, ss);
QuickSort(A, p, q - 1, ss);
QuickSort(A, q + 1, r, ss);
}
}
static void InsertionSort <T>(IList <T> items, int p, int r, SortStats ss)
where T : IComparable <T>
{
for (int i = p; i < r; i++)
{
T x = items[i];
int j = i - 1;
while (j >= 0 && items[j].CompareTo(x) > 0)
{
ss.Compares++;
items[j + 1] = items[j];
j--;
ss.Swaps++;
}
items[j + 1] = x;
}
}
static int Partition <T>(IList <T> A, int p, int r, SortStats ss)
where T : IComparable <T>
{
T x = A[r];
int i = p - 1;
for (int j = p; j < r; ++j)
{
ss.Compares++;
if (A[j].CompareTo(x) <= 0)
{
ss.Swaps++;
Swap(A, ++i, j);
}
}
ss.Swaps++;
Swap(A, ++i, r);
return(i);
}
private static void MergeInPlace <T>(IList <T> input, int startA, int startB, int endB, SortStats ss, T[] scratch)
where T : IComparable <T>
{
var c = new T[endB - startA + 1];
int ap = startA, bp = startB, cp = 0;
while (cp < endB - startA + 1)
{
ss.Compares++;
if (bp > endB || (ap <= (startB - 1) && (input[ap].CompareTo(input[bp]) < 0)))
{
c[cp] = input[ap];
ap++;
}
else
{
c[cp] = input[bp];
bp++;
}
cp++;
}
for (int i = startA; i <= endB; i++)
{
input[i] = c[i - startA];
}
}
public static void MergeSortInPlace <T>(IList <T> input, int startIndex, int endIndex, SortStats ss, T[] scratch)
where T : IComparable <T>
{
if (endIndex - startIndex <= 0)
{
return;
}
int half = (endIndex - startIndex + 1) / 2;
MergeSortInPlace(input, startIndex, startIndex + half - 1, ss, scratch);
MergeSortInPlace(input, startIndex + half, endIndex, ss, scratch);
MergeInPlace(input, startIndex, startIndex + half, endIndex, ss, scratch);
}
