小顶堆大顶堆的概念大家应该都很熟悉了，如果不了解，可以搜索一下，网上很多介绍，而且很多源码实现，都很简单。

不过从网上看了一些堆的实现，都是用数组的。但是数组有一个缺陷，需要扩展时，就要复制原来的内存，申请新的空间。所以我在想能不能用链表，发现还真可以，就凑凑写了个代码。最后代码是写完了，发现其实链表没有必要，而且会占用更多的内存，尤其是对于那种int型变量，过多的指针真是浪费了大量内存。如果真要优化，可以针对数组做优化，链表不是出路。

反正代码写完了，拿出来晾一晾，呵呵。

代码在VS2008上编译测试通过，不过测试用例很简单。

#ifndef _HNWYLLMM_HEAP_H
#define _HNWYLLMM_HEAP_H

#include <map>
#include <iostream>
#include <cassert>

template<typename elem_t, typename cmp_func_t = std::less<elem_t> >
class cheap
{
public:
	cheap() : m_root(NULL), m_last(NULL), m_count(0)
	{

	}
	~cheap()
	{
		destroy() ;
	}

	int init()
	{
		m_last = m_root = NULL ;
		m_count = 0 ;
		return 0 ;
	}
	
	int	destroy()
	{
		cheap_node *node = m_root ;
		cheap_node *next = NULL ;
		while (node)
		{
			next = node->_next ;
			delete node ;
			node = next ;
		}
		m_root = m_last = NULL ;
		m_count ;
	}

	int size() const {return m_count ;}
	
	int	push(const elem_t &ele)
	{
		cheap_node *node = new cheap_node(ele) ;
		if (!node)
			return -1 ;
		
		m_count++ ;
		
		if (!m_last)
			m_root = m_last = node ;
		else
		{
			cheap_node *parent = m_last->_parent ;
			if (!parent)
			{
				parent = m_last ;
				m_last->_left = node ;
			}
			else if (parent->_left == m_last)
			{
				parent->_right = node ;
			}
			// parent's right child
			else if (parent->_next)
			{
				parent = parent->_next ;
				parent->_left = node ;
			}
			else
			{
				assert(0) ;
				parent = m_root ;
				for (parent = m_root ; parent->_left ; parent = parent->_left) ;
				
				parent->_left = node ;
			}
			m_last->_next = node ;
			
			node->_parent = parent ;
			node->_prev = m_last ;
			
			m_last = node ;			
		}
		
		// 调整
		cheap_node *next = m_last ;
		cheap_node *parent = NULL ;
		while ((parent = next->_parent) && 
				m_cmp_func(next->_data, parent->_data)
				)
		{
			elem_t tmp = next->_data ;
			next->_data = parent->_data ;
			parent->_data = tmp ;
		}
		
		return 0 ;
	}
	
	int	pop(elem_t &ele)
	{
		if (!m_root)
			return -1 ;
		
		ele = m_root->_data ;
		m_count-- ;
		
		if (m_last == m_root)
		{
			delete m_last ;
			m_root = m_last = NULL ;
			return 0 ;
		}
		
		m_root->_data = m_last->_data ;
		m_last->_data = NULL ;
		if (m_last->_parent)
		{
			if (m_last->_parent->_left == m_last)
			{
				m_last->_parent->_left = NULL ;
			}
			else
			{
				m_last->_parent->_right = NULL ;
			}
		}
		m_last = m_last->_prev ;
		delete m_last->_next ;
		m_last->_next = NULL ;
		
		for (cheap_node *last = m_root, *node = NULL ; last ;  last = node)
		{	
			if (last->_right)
			{
				if (m_cmp_func(last->_left->_data, last->_right->_data))
				{
					node = last->_left ;
				}
				else
					node = last->_right ;
			}
			else
				node = last->_left ;
			
			if (node)
			{
				if (m_cmp_func(node->_data, last->_data))
				{
					elem_t tmp = last->_data ;
					last->_data = node->_data ;
					node->_data = tmp ;
				}
				else
					break ;
			}
		}
		
		return 0 ;
	}

	friend cheap &operator <<(cheap &heap, const elem_t &ele)
	{
		heap.push(ele) ;
		return heap ;
	}

	friend cheap &operator >>(cheap &heap, elem_t &ele)
	{
		heap.pop(ele) ;
		return heap ;
	}

	void dump(std::ostream &os)
	{
		os << "dump: \n" ;
		int i = 1, lvl = 0 ;
		for (cheap_node *node = m_root ; node ; node = node->_next, i++)
		{
			os << node->_data << '\t' ;
			if (i == (1 << lvl) )
			{
				os << std::endl ;
				i = 0 ;
				lvl++ ;
			}
		}
		os << std::endl ;
	}
	
private:
	// 堆中的一个节点
	// 包含了树的结构和链表的结构
	// 还有一个数据
	class cheap_node
	{
	public:
		cheap_node *		_parent ;
		cheap_node *		_left ;
		cheap_node *		_right ;
		
		cheap_node *		_next ;
		cheap_node *		_prev ;
		
		elem_t 				_data ;
	public:
		cheap_node(const elem_t &ele) :
			_parent(NULL),
			_left(NULL),
			_right(NULL),
			_next(NULL),
			_prev(NULL),
			_data(ele)
		{
		}
		
		~cheap_node()
		{
		}
	};
	
private:
	cheap_node *	m_root ;		// 第一个数据
	cheap_node *	m_last ;		// 最后一个数据
	int				m_count ;		// 统计个数
	cmp_func_t		m_cmp_func ;	// 用来做比较的函数
};

#endif  // _HNWYLLMM_HEAP_H

测试文件：

main.cpp

#include <iostream>

#include "heap_array.h"

using namespace std ;

int main(void)
{
	cheap<int> heap ;
	heap.push(6) ;
	heap.dump(cout ) ;

//	heap.push(5) ;
//	heap << 100 << 5 << 9 << 11 ;
	heap << 100 ; heap.dump(cout) ;
	heap << 5 ; heap.dump(cout) ;
	heap << 9 ; heap.dump(cout) ;
	heap << 11 ; heap.dump(cout) ;

	heap.dump(cout) ;

	int num ;
	while (0 == heap.pop(num))
	{
		cout << num << endl ;
		heap.dump(cout) ;
	}
	return 0 ;
}