算法笔记(堆实现的最大优先队列)

采用最大堆实现的优先队列，QueueElement是队列元素类，包含一个卫星数据成员和一个权重Key值:

public class QueueElement<T> { public int KeyValue{get;internal set;} public T Element{get;private set;} public QueueElement(T Item,int KeyVal) { KeyValue = KeyVal; Element = Item; } } public class MaxHeapQueue<T> { private List<QueueElement<T>> _queueValues = new List<QueueElement<T>>(); public int Count { get { return _queueValues.Count; } } public T GetMaximum() { return _queueValues[0].Element; } public T ExtractMax() { if (_queueValues.Count <= 0) { throw new Exception("队列为空"); } T theMax = _queueValues[0].Element; int theTail = Count -1; _queueValues[0] = _queueValues[theTail]; _queueValues.RemoveAt(theTail); MaxHeapify(0); return theMax; } public void MaxHeapify(int i) { int HeapSize = Count; int theL = HeapL(i); int theR = HeapR(i); int thelargest = i; if (theL < HeapSize && _queueValues[theL].KeyValue> _queueValues[thelargest].KeyValue) { thelargest = theL; } if (theR < HeapSize && _queueValues[theR].KeyValue> _queueValues[thelargest].KeyValue) { thelargest = theR; } if (thelargest != i) { SwapElement(i, thelargest); MaxHeapify(thelargest); } } public void IncreaseKey(Func<T, bool> SelectFunc, int NewKey) { int theIndex = -1; for (int i = 0; i < Count; i++) { if (SelectFunc(_queueValues[i].Element) == true) { theIndex = i; break; } } if (theIndex < 0) { return; } if (_queueValues[theIndex].KeyValue >= NewKey) { return; } _queueValues[theIndex].KeyValue = NewKey; UpAdjust(theIndex); } private void UpAdjust(int i) { int theIndex = i; int thePIndex = HeapP(theIndex); while (thePIndex >= 0 && _queueValues[theIndex].KeyValue > _queueValues[thePIndex].KeyValue) { SwapElement(thePIndex, theIndex); theIndex = thePIndex; thePIndex = HeapP(theIndex); } } public void IncreaseKey(int i, int NewKey) { int theIndex = i; if (_queueValues[theIndex].KeyValue >= NewKey) { return; } _queueValues[theIndex].KeyValue = NewKey; int thePIndex = HeapP(theIndex); while (thePIndex >= 0 && _queueValues[theIndex].KeyValue > _queueValues[thePIndex].KeyValue) { SwapElement(thePIndex, theIndex); theIndex = thePIndex; thePIndex = HeapP(theIndex); } } public void HeapDelete(Func<T, bool> SelectFunc) { int theIndex = -1; for (int i = 0; i < Count; i++) { if (SelectFunc(_queueValues[i].Element) == true) { theIndex = i; break; } } if (theIndex < 0) { return; } SwapElement(theIndex, Count - 1); _queueValues.RemoveAt(Count-1); if (theIndex < Count) { int theP = HeapP(theIndex); bool theUp = false; if (theP >= 0) { if (_queueValues[theIndex].KeyValue > _queueValues[theP].KeyValue) { UpAdjust(theIndex); theUp = true; } } if(theUp==false) { MaxHeapify(theIndex); } } } private void SwapElement(int i, int j) { QueueElement<T> theTmp = _queueValues[i]; _queueValues[i] = _queueValues[j]; _queueValues[j] = theTmp; } public void HeapInsert(T Element, int Key) { _queueValues.Add(new QueueElement<T>(Element, int.MinValue)); IncreaseKey(Count-1, Key); } private int HeapL(int i) { return i * 2 + 1; } private int HeapR(int i) { return i * 2 + 2; } private int HeapP(int i) { return (i + 1) / 2 - 1; } }