public void Test2()
{
var random = new Random();
for (int j = 0; j < 100; j++)
{
var randomSource = Enumerable.Range(0, 200).Select(_ => random.NextDouble() * 50).ToArray();
var pool = ArrayPool <int> .Shared.Rent(randomSource.Length);
var indices = pool.AsSpan(0, randomSource.Length);
int n = random.Next(200);
QuickSelect.Iota(indices);
QuickSelect.Execute(randomSource, indices, n);
var pivot = randomSource[indices[n]];
for (int i = 0; i < n; i++)
{
var result = Comparer <double> .Default.Compare(randomSource[indices[i]], pivot);
Assert.IsTrue(result < 0);
}
for (int i = n; i < randomSource.Length; i++)
{
var result = Comparer <double> .Default.Compare(randomSource[indices[i]], pivot);
Assert.IsTrue(0 <= result);
}
ArrayPool <int> .Shared.Return(pool);
}
}
public void Test7()
{
ReadOnlySpan <int> randomSource = Enumerable.Range(0, 200).Shuffle().ToArray().AsSpan();
var pool = ArrayPool <int> .Shared.Rent(randomSource.Length);
var indices = pool.AsSpan(0, randomSource.Length);
QuickSelect.Iota(indices);
//Get 50 <= item < 60
int n = 50;
QuickSelect.Execute(randomSource, indices, 50);
QuickSelect.Execute(randomSource, indices[50..], 10);
public void Test2_3()
{
var random = new Random();
for (int k = 0; k < 100; k++)
{
ReadOnlySpan <double> randomSource =
Enumerable.Range(0, 200).Select(_ => random.NextDouble() * 50).ToArray().AsSpan();
var pool = ArrayPool <int> .Shared.Rent(randomSource.Length);
var indices = pool.AsSpan(0, randomSource.Length);
QuickSelect.Iota(indices);
int prevN = 0;
for (int j = 0; j < 2; j++)
{
var tmpIndices = indices.Slice(prevN, indices.Length - prevN);
int n = random.Next(tmpIndices.Length);
QuickSelect.Execute(randomSource, tmpIndices, n);
var pivot = randomSource[tmpIndices[n]];
for (int i = 0; i < n; i++)
{
var result = Comparer <double> .Default.Compare(randomSource[tmpIndices[i]], pivot);
Assert.IsTrue(result <= 0);
}
for (int i = n; i < tmpIndices.Length; i++)
{
var result = Comparer <double> .Default.Compare(randomSource[tmpIndices[i]], pivot);
Assert.IsTrue(0 <= result);
}
prevN = n + prevN;
}
ArrayPool <int> .Shared.Return(pool);
}
}
public void Test4()
{
var random = new Random();
//var randomSource = new int[] { 1, 2, 3, 4, 4, 4, 4, 4, 5, 6, 7, 8 };
Span <int> randomSource = new int[] { 4, 4, 8, 1, 2, 5, 4, 4, 4, 6, 7, 3 }.AsSpan();
var pool = ArrayPool <int> .Shared.Rent(randomSource.Length);
var indices = pool.AsSpan(0, randomSource.Length);
//int n = random.Next(randomSource.Length);
int n = 6;
QuickSelect.Iota(indices);
QuickSelect.Execute <int>(randomSource, indices, n);
//or
//QuickSelect.Execute((ReadOnlySpan<int>)randomSource, indices, n);
//or
//QuickSelect.Execute(randomSource, indices, n, Comparer<int>.Default);
DebugView <int>(randomSource, indices, n);
var pivot = randomSource[indices[n]];
for (int i = 0; i < n; i++)
{
var result = Comparer <double> .Default.Compare(randomSource[indices[i]], pivot);
Assert.IsTrue(result <= 0);
}
for (int i = n + 1; i < randomSource.Length; i++)
{
var result = Comparer <double> .Default.Compare(randomSource[indices[i]], pivot);
Assert.IsTrue(0 <= result);
}
ArrayPool <int> .Shared.Return(pool);
}