/// <summary> /// Decreases the value of a specified item. /// </summary> /// <param name="item">The value of the item to be changed.</param> /// <param name="newValue">The new value of the item.</param> public bool DecreaseKey(T item, T newValue) { PairingHeap <T> heap; LinkedListNode <PairingHeap <T> > node; if (this.Find(item, out heap, out node)) { PairingMinHeap <T> minHeap = (PairingMinHeap <T>)heap; minHeap.root = newValue; if (node == null) { return(true); } node.List.Remove(node); do { minHeap = (PairingMinHeap <T>)minHeap.parent; minHeap.Count -= heap.Count; }while (minHeap.parent != null); this.Merge(heap); return(true); } return(false); }
public void PairingMinHeap_Test() { int nodeCount = 1000 * 10; //insert test var tree = new PairingMinHeap <int>(); for (int i = 0; i <= nodeCount; i++) { tree.Insert(i); } for (int i = 0; i <= nodeCount; i++) { tree.DecrementKey(i, i - 1); } int min = 0; for (int i = 0; i <= nodeCount; i++) { min = tree.ExtractMin(); Assert.AreEqual(min, i - 1); } //IEnumerable tests. Assert.AreEqual(tree.Count, tree.Count()); var rnd = new Random(); var testSeries = Enumerable.Range(0, nodeCount - 1).OrderBy(x => rnd.Next()).ToList(); foreach (var item in testSeries) { tree.Insert(item); } for (int i = 0; i < testSeries.Count; i++) { var decremented = testSeries[i] - rnd.Next(0, 1000); tree.DecrementKey(testSeries[i], decremented); testSeries[i] = decremented; } testSeries.Sort(); for (int i = 0; i < nodeCount - 2; i++) { min = tree.ExtractMin(); Assert.AreEqual(testSeries[i], min); } //IEnumerable tests. Assert.AreEqual(tree.Count, tree.Count()); }
/// <summary> /// Merges a heap into this one. /// </summary> /// <param name="other">The heap to merge into this one.</param> public override void Merge(PairingHeap <T> other) { PairingMinHeap <T> heap = other as PairingMinHeap <T>; if (heap == null) { this.AddRange(other); return; } if (heap.Count == 0) { return; } if (this.Count == 0) { this.root = heap.root; this.children = heap.children; this.Count = heap.Count; return; } this.Count += heap.Count; if (this.root.CompareTo(heap.root) <= 0) { this.children.AddFirst(heap); heap.parent = this; } else { PairingMinHeap <T> newHeap = new PairingMinHeap <T>(this.root, this.children, this.Count - heap.Count); this.root = heap.root; this.children = heap.children; this.children.AddFirst(newHeap); newHeap.parent = this; } }
public void PairingMinHeap_Test() { int nodeCount = 1000 * 10; //insert test var tree = new PairingMinHeap <int>(); var nodePointers = new List <PairingHeapNode <int> >(); for (int i = 0; i <= nodeCount; i++) { var node = tree.Insert(i); nodePointers.Add(node); } for (int i = 0; i <= nodeCount; i++) { nodePointers[i].Value--; tree.DecrementKey(nodePointers[i]); } int min = 0; for (int i = 0; i <= nodeCount; i++) { min = tree.ExtractMin(); Assert.AreEqual(min, i - 1); } nodePointers.Clear(); var rnd = new Random(); var testSeries = Enumerable.Range(0, nodeCount - 1).OrderBy(x => rnd.Next()).ToList(); foreach (var item in testSeries) { nodePointers.Add(tree.Insert(item)); } min = tree.ExtractMin(); nodePointers = nodePointers.Where(x => x.Value != min).ToList(); var resultSeries = new List <int>(); for (int i = 0; i < nodePointers.Count; i++) { nodePointers[i].Value = nodePointers[i].Value - rnd.Next(0, 1000); tree.DecrementKey(nodePointers[i]); } foreach (var item in nodePointers) { resultSeries.Add(item.Value); } resultSeries.Sort(); for (int i = 0; i < nodeCount - 2; i++) { min = tree.ExtractMin(); Assert.AreEqual(resultSeries[i], min); } }