private static IEnumerable <int> ExtractAll(PairingHeap <int> heap)
{
while (heap.TryExtractMinimum(out var min))
{
yield return(min);
}
}
public void GetItem_SingleElement_ReturnsValue()
{
var heap = new PairingHeap <int>();
var pointer = heap.Insert(42);
Assert.That(heap[pointer], Is.EqualTo(42));
}
public void Insert_Empty_IsNotEmpty()
{
var heap = new PairingHeap <int>();
heap.Insert(0);
Assert.That(heap.IsEmpty, Is.False);
}
public void ExtractMinimum_SingleElement_ReturnsElement()
{
var heap = new PairingHeap <int>();
heap.Insert(42);
Assert.That(heap.ExtractMinimum(), Is.EqualTo(42));
}
public void Remove_AllElements_IsEmpty(params int[] values)
{
var heap = new PairingHeap <int>();
var pointers = values.Select(heap.Insert).ToList();
pointers.ForEach(heap.Remove);
Assert.That(heap.IsEmpty, Is.True);
}
public void Merge_WithEmpty_CountUnchanged()
{
var heap = new PairingHeap <int>();
heap.Insert(0);
heap.Merge(new());
Assert.That(heap.Count(), Is.EqualTo(1));
}
public void Merge_WithNonEmpty_CountChanged()
{
var heap = new PairingHeap <int>();
var other = new PairingHeap <int>();
other.Insert(0);
heap.Merge(other);
Assert.That(heap.Count(), Is.EqualTo(1));
}
public void ExtractMinimum_SingleElement_RemovesElement()
{
var heap = new PairingHeap <int>();
heap.Insert(0);
heap.ExtractMinimum();
Assert.That(heap.IsEmpty, Is.True);
Assert.That(() => heap.Minimum, Throws.InvalidOperationException);
}
public void Merge_WithNonEmpty_ClearsArgument()
{
var heap = new PairingHeap <int>();
var other = new PairingHeap <int>();
other.Insert(0);
heap.Merge(other);
Assert.That(other.IsEmpty, Is.True);
}
/// <summary>
/// Destructively merges another heap.
/// </summary>
/// <param name="heap">Another heap with elements to add to this heap.</param>
/// <remarks><paramref name="heap"/> is emptied in the process.</remarks>
public void Merge(PairingHeap <T> heap)
{
if (heap._head == null)
{
return;
}
this._head = this._head == null ? heap._head : this.Meld(heap._head, this._head);
heap._head = null;
}
public void Minimum_ManyElements_IsCorrect(params int[] values)
{
var heap = new PairingHeap <int>();
foreach (var value in values)
{
heap.Insert(value);
}
Assert.That(heap.Minimum, Is.EqualTo(values.Min()));
}
public void Insert_MultipleTimesIntoEmpty_CountIsCorrect(int size)
{
var heap = new PairingHeap <int>();
for (var i = 0; i < size; i++)
{
heap.Insert(0);
}
Assert.That(heap.Count(), Is.EqualTo(size));
}
public void Remove_MiddleElement_DecreasesCount()
{
var heap = new PairingHeap <int>();
heap.Insert(2);
var pointer = heap.Insert(1);
heap.Insert(0);
heap.Remove(pointer);
Assert.That(heap.Count(), Is.EqualTo(2));
}
public void Decrease_MiddleElement_ExtractsAllElementsCorrectly()
{
var heap = new PairingHeap <int>();
heap.Insert(2);
var pointer = heap.Insert(1);
heap.Insert(0);
heap.Decrease(pointer, -1);
var elements = ExtractAll(heap).ToArray();
Assert.That(elements, Is.EqualTo(new[] { -1, 0, 2 }));
}
public void Remove_ManyElements_DecreasesCount()
{
var heap = new PairingHeap <int>();
for (var i = 0; i < 15; i++)
{
heap.Insert(i);
}
var pointer = heap.Insert(5);
heap.Remove(pointer);
Assert.That(heap.Count(), Is.EqualTo(15));
}
public void Merge_TwoNonEmpty_ExtractsAllElementsCorrectly()
{
var heap = new PairingHeap <int>();
heap.Insert(0);
heap.Insert(2);
var other = new PairingHeap <int>();
other.Insert(1);
other.Insert(3);
heap.Merge(other);
Assert.That(ExtractAll(heap), Is.EqualTo(new[] { 0, 1, 2, 3 }));
}
public void ExtractMinimum_ManyElements_CanSortSequence(params int[] values)
{
var heap = new PairingHeap <int>();
foreach (var value in values)
{
heap.Insert(value);
}
var sorted = new List <int>();
while (!heap.IsEmpty)
{
sorted.Add(heap.ExtractMinimum());
}
Assert.That(sorted, Is.EqualTo(values.OrderBy(x => x).ToList()));
}
public void ExtractMinimum_Empty_Throws()
{
var heap = new PairingHeap <int>();
Assert.That(() => heap.ExtractMinimum(), Throws.InvalidOperationException);
}
public void Ctor_DefaultComparer_CountIsZero()
{
var heap = new PairingHeap <int>(Comparer <int> .Default);
Assert.That(heap.Count(), Is.Zero);
}
public void Count_Empty_IsZero()
{
var heap = new PairingHeap <int>();
Assert.That(heap.Count(), Is.Zero);
}