Heap< T, Cmp > Class Template Reference

List of all members.

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Detailed Description

template<class T, class Cmp>
class Heap< T, Cmp >

General-purpose heap.

This class implements a general purpose heap. The element type T and the ordering function (via class Cmp) are passed in as parameters to the Heap template.

This heap sifts the LARGEST elements to the top and the SMALLEST elements to the bottom, according tho the comparison function, Cmp.gt(). Thus the "heap property" is that value(Parent(i)) gt value(i) for each element i in the heap.

An element anywhere in the heap can be changed (by an outsider- not by the heap template) and the heap property can be restored, but he who changes the element must know whether the element's key value increased or decreased. Since we're sifting "large" elements to the top of the heap, if the element's key value increases, the element must be sifted UP, and if its value decreases, it must be sifted down. The methods IncreaseN and DecreaseN handle these cases.

The heap has the following worst case run times:

• create initial heap O(n)
• retrieve first element O(1)
• retrieve second element O(1)
• replace first element O(log n)
• delete first element O(log n)
• add new element O(log n)
• increment/decrement key for any element O(log n)

The comparison class, Cmp, must have the member functions gt (T* left, T* right) returns true iff left > right

RemoveFirst always removes the largest element.

Definition at line 79 of file w_heap.h.

Public Member Functions
	Heap (const Cmp &cmpFunction, int initialNumElements=32)
	~Heap ()
int	NumElements () const
	How many elements in the heap?
T	RemoveFirst ()
	Take top/largest element off.
T	RemoveN (int i)
	Remove element from the middle.
void	AddElement (const T &elem)
	Put in heap and recompute to restore heap property.
void	AddElementDontHeapify (const T &elem)
	Put in heap but do NOT recompute to restore heap property.
void	Heapify ()
	Recompute to restore heap property.
T &	First ()
	Get reference to top of heap (do not remove).
T &	Value (int i)
	Get reference arbitrary element (do not remove).
const T &	Second () const
	Get reference element just below top (do not remove).
void	ReplacedFirst ()
	Inform heap that I replaced the top: recompute, but more efficient than Heapify().
void	IncreasedN (int i)
	Inform heap that element i must rise in heap to restore heap property. More efficient than general Heapify().
void	DecreasedN (int i)
	Inform heap that element i must drop in heap to restore heap property. More efficient than general Heapify().
void	CheckHeap () const
	Check heap property.
void	Print (ostream &out) const
	Dump heap.
bool	HeapProperty (int root) const
	Check heap property from given root to the bottom.
Protected Member Functions
int	LeftChild (int i) const
int	RightChild (int i) const
int	RightSibling (int i) const
int	Parent (int i) const
void	PrintRoot (ostream &out, int rootElem, int indentLevel) const
void	CheckHeapRoot (int rootElem) const
bool	HeapProperty (int lower, int upper) const
void	SiftDown (int rootElem)
void	SiftUp (int rootElem)
void	GrowElements (int newSize)
Protected Attributes
int	numElements
int	maxNumElements
T *	elements
const Cmp &	cmp

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The documentation for this class was generated from the following file:

• src/fc/w_heap.h

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