优先级队列，代码参考范例
一个看起来比较规范的代码：
1、版本信息
2、预处理信息
3、库函数引用
4、泛型编程
5、宏定义
6、复制构造函数
7、内敛函数
8、变量命名规范
9、代码的时间空间效率
10、错误恢复能力
11、规范的注释和缩进
代码范例：
/***************************************
** Project:PriorityQueue
** File:priqueue.h
** Edition:v1.0.0 Demo
** Coder:KingsamChen [MDSA Group]
** Last Modify:2011-9-1
****************************************/
#if _MSC_VER > 1000
#pragma once
#endif
#ifndef _PRIQUEUE_05232021_A052_400f_ADD6_8FA21FDCBF7E
#define _PRIQUEUE_05232021_A052_400f_ADD6_8FA21FDCBF7E
#include <cassert>
#include <cstdio>
#define PARENT(x) (((x) - 1) >> 1)
#define LEFTCHILD(x) (((x) << 1) + 1)
#define RIGHTCHILD(x) (((x) + 1) << 1)
template<typename T>
class CPriQueue
{
public:
typedef int pos;
public:
CPriQueue();
CPriQueue(const CPriQueue& q);
~CPriQueue();
public:
CPriQueue& operator =(const CPriQueue& q);
void BuildHeap(const T ary[], int count);
void Insert(const T& ele);
T ExtractMin();
inline T Min() const;
inline int GetCount() const;
inline bool IsEmpty() const;
inline bool IsFull() const;
pos Find(const T& ele) const;
void DecreaseKey(pos p, unsigned int det);
void IncreaseKey(pos p, unsigned int det);
void Delete(pos p);
// diagnostic interface
#if _DEBUG
void DgPrint();
#endif
private:
void PercolateUp(int i, const T& ele);
void PercolateDown(int i, const T& ele);
private:
enum{INI_CAPCITY = 50, NOT_FOUND = -1};
T* m_pHeap;
int m_capcity;
int m_count;
};
template<typename T>
CPriQueue<T>::CPriQueue() : m_count(0)
{
m_pHeap = new T[INI_CAPCITY];
assert(m_pHeap != NULL);
m_capcity = INI_CAPCITY;
}
template<typename T>
CPriQueue<T>::CPriQueue(const CPriQueue& q) : m_capcity(q.m_capcity),
m_count(q.m_count)
{
m_pHeap = new T[m_capcity];
assert(m_pHeap != NULL);
// the element may have internal handle pointing to the extra data outside
// assume that the object already overloaded operator =
for (int i = 0; i < m_count; ++i)
{
m_pHeap[i] = q.m_pHeap[i];
}
}
template<typename T>
CPriQueue<T>::~CPriQueue()
{
if (m_pHeap != NULL)
{
delete [] m_pHeap;
m_pHeap = NULL;
m_capcity = 0;
m_count = 0;
}
}
template<typename T>
CPriQueue<T>& CPriQueue<T>::operator =(const CPriQueue& q)
{
if (m_capcity < q.m_count)
{
// need to expand
assert(false);
}
m_count = q.m_count
for (int i = 0; i < m_count; ++i)
{
m_pHeap[i] = q.m_pHeap[i];
}
return *this;
}
template<typename T>
void CPriQueue<T>::Insert(const T& ele)
{
if (IsFull())
{
// Logs error or expands capcity of the heap
assert(false);
}
// new element may violate heap property
PercolateUp(m_count, ele);
++m_count;
}
/*
Description:
Adjusts the specific element which may violate the heap property
upward.
Parameters:
i[in] - the position in the heap of the specific element.
ele[in] - a copy of the element. It's used to make the function more
efficient. Do not have this parameter refered to the element directly.
It may possible change the value of the ele while adjusting.
Return Value:
none
*/
template<typename T>
void CPriQueue<T>::PercolateUp(int i, const T& ele)
{
for (int p = PARENT(i); ele < m_pHeap[p]; p = PARENT(p))
{
// reaches the root
if (0 == i)
{
break;
}
m_pHeap[i] = m_pHeap[p];
i = p;
}
m_pHeap[i] = ele;
}
template<typename T>
T CPriQueue<T>::ExtractMin()
{
assert(!IsEmpty());
T ret(m_pHeap[0]);
// new root violates the heap property
PercolateDown(0, m_pHeap[--m_count]);
return ret;
}
/*
Description:
It is Similar to the function PercolateUp but downward.
Parameters:
i[in] - the position in the heap of the specific element.
ele[in] - the same as in PercolateUp
Return Value:
none
*/
template<typename T>
void CPriQueue<T>::PercolateDown(int i, const T& ele)
{
for (; LEFTCHILD(i) < m_count;)
{
// the node may have only left child
int iL = LEFTCHILD(i);
int iR = RIGHTCHILD(i);
int iMin = iR < m_count ? (m_pHeap[iL] < m_pHeap[iR] ? iL : iR) : iL;
if (m_pHeap[iMin] < ele)
{
m_pHeap[i] = m_pHeap[iMin];
i = iMin;
}
else
{
break;
}
}
m_pHeap[i] = ele;
}
template<typename T>
inline T CPriQueue<T>::Min() const
{
assert(!IsEmpty());
return m_pHeap[0];
}
template<typename T>
inline int CPriQueue<T>::GetCount() const
{
return m_count;
}
template<typename T>
inline bool CPriQueue<T>::IsEmpty() const
{
return 0 == m_count ? true : false;
}
template<typename T>
inline bool CPriQueue<T>::IsFull() const
{
return m_capcity == m_count ? true : false;
}
/*
Description:
Returns the position of the specific element to be found. The function
takes O(N) time
Parameters:
ele[in] - the element we search for
Return Value:
The function returns NOT_FOUND if the specific element is not found
otherwise the return value indicates the position of the element
*/
template<typename T>
typename CPriQueue<T>::pos CPriQueue<T>::Find(const T& ele) const
{
pos index = NOT_FOUND;
for (int i = 0; i < m_count; ++i)
{
if (m_pHeap[i] == ele)
{
index = i;
break;
}
}
return index;
}
template<typename T>
void CPriQueue<T>::DecreaseKey(pos p, unsigned int det)
{
assert(p >= 0);
m_pHeap[p] -= det;
T newEle(m_pHeap[p]);
// adjusts the order property
PercolateUp(p, newEle);
}
template<typename T>
void CPriQueue<T>::IncreaseKey(pos p, unsigned int det)
{
assert(p >= 0);
m_pHeap[p] += det;
T newEle(m_pHeap[p]);
PercolateDown(p, newEle);
}
template<typename T>
void CPriQueue<T>::Delete(pos p)
{
assert(p >= 0);
int det = m_pHeap[p] - m_pHeap[0] + 1;
DecreaseKey(p, det);
ExtractMin();
}
/*
Description:
Builds up the heap from an array
Parameters:
ary[in] - the array contains elements
count[in] - indicates the counts of the elements in array
Return Value:
none
*/
template<typename T>
void CPriQueue<T>::BuildHeap(const T ary[], int count)
{
assert(m_capcity >= count);
for (int i = 0; i < count; ++i)
{
m_pHeap[i] = ary[i];
}
m_count = count;
for (int i = PARENT(count - 1); i >= 0; --i)
{
T eleMov(m_pHeap[i]);
PercolateDown(i, eleMov);
}
}
#if _DEBUG
template<typename T>
void CPriQueue<T>::DgPrint()
{
for (int i = 0; i < m_count; ++i)
{
wprintf_s(L"%d\t", m_pHeap[i]);
}
wprintf_s(L"\n");
}
#endif
#endif
