时间：2023-03-11 11:00:57 | 栏目：C代码 | 点击：次
由于priority_queue是一种容器适配器，适配的是vector,我们在vector中已经写过它的构造函数了。故priority_queue在此不需要多余的其他构造函数。
// 创造空的优先级队列
priority_queue():m_priority_queue()
{
}
template<class Iterator>
priority_queue(Iterator first, Iterator last)
: m_priority_queue(first, last)
{
// 将m_priority_queue中的元素调整成堆的结构
int count = m_priority_queue.size();
int root = ((count - 2) >> 1);
for (; root >= 0; root--)
AdjustDown(root);
}
功能：push函数用来往堆中(尾部)插入一个元素，并向上调整成新的堆。
//向上调整
void AdjustUp(int child)
{
int parent = (child-1)>>1;
while (child > 0)
{
//其中c是一个对象，用该对象去调用仿函数来进行比较
if (c(m_priority_queue[parent], m_priority_queue[child]))
{
std::swap(m_priority_queue[parent], m_priority_queue[child]);
child = parent;
parent = (child - 1) >> 1;
}
else
{
break;
}
}
}
void push(const T& val)
{
m_priority_queue.push_back(val);
AdjustUp(m_priority_queue.size()-1);
}
功能：pop函数弹出堆顶元素。具体步骤是：堆顶元素与最后一个数字进行交换位置。之后在进行尾删来删除堆顶。再重新向下调堆。
//向下调堆
void AdjustDown(int parent)
{
int child = (parent << 1) + 1;
int size = static_cast<int>(m_priority_queue.size());
while (child< size)
{
if (child + 1 < size && c(m_priority_queue[child],m_priority_queue[child + 1]) )
{
++child;
}
if (c(m_priority_queue[parent], m_priority_queue[child]))
{
std::swap(m_priority_queue[parent], m_priority_queue[child]);
parent = child;
child = (parent << 1) + 1;
}
else
{
break;
}
}
}
void pop()
{
assert(!m_priority_queue.empty());
std::swap(m_priority_queue[0], m_priority_queue[m_priority_queue.size()- 1]);
m_priority_queue.pop_back();
AdjustDown(0);
}
功能：用来获取堆中的元素个数。
size_t size() const
{
return m_priority_queue.size();
}
功能：用来判断堆中是否为空。
bool empty() const
{
return m_priority_queue.empty();
}
功能：用来获取堆顶的元素。
T& top()
{
return m_priority_queue.front();
}
const T& top() const
{
return m_priority_queue.front();
}
代码实现
#pragma once
#define _CRT_SECURE_NO_WARNINGS 1
#include<iostream>
#include<vector>
#include<assert.h>
namespace ZJ
{
template<class T>
class less
{
public:
bool operator() (const T& x, const T& y) const
{
return x < y;
}
};
template<class T>
class greater
{
public:
bool operator() (const T& x, const T& y) const
{
return x > y;
}
};
template<class T,class Container=std::vector<T>, class Compare = ZJ::less<T>>
class priority_queue
{
public:
// 创造空的优先级队列
priority_queue():m_priority_queue()
{
}
template<class Iterator>
priority_queue(Iterator first, Iterator last)
: m_priority_queue(first, last)
{
// 将m_priority_queue中的元素调整成堆的结构
int count = m_priority_queue.size();
int root = ((count - 2) >> 1);
for (; root >= 0; root--)
AdjustDown(root);
}
public:
//向上调整
void AdjustUp(int child)
{
int parent = (child-1)>>1;
while (child > 0)
{
if (c(m_priority_queue[parent], m_priority_queue[child]))
{
std::swap(m_priority_queue[parent], m_priority_queue[child]);
child = parent;
parent = (child - 1) >> 1;
}
else
{
break;
}
}
}
void push(const T& val)
{
m_priority_queue.push_back(val);
AdjustUp(m_priority_queue.size()-1);
}
void AdjustDown(int parent)
{
int child = (parent << 1) + 1;
int size = static_cast<int>(m_priority_queue.size());
while (child< size)
{
if (child + 1 < size && c(m_priority_queue[child],m_priority_queue[child + 1]) )
{
++child;
}
if (c(m_priority_queue[parent], m_priority_queue[child]))
{
std::swap(m_priority_queue[parent], m_priority_queue[child]);
parent = child;
child = (parent << 1) + 1;
}
else
{
break;
}
}
}
void pop()
{
assert(!m_priority_queue.empty());
std::swap(m_priority_queue[0], m_priority_queue[m_priority_queue.size()- 1]);
m_priority_queue.pop_back();
AdjustDown(0);
}
size_t size() const
{
return m_priority_queue.size();
}
T& top()
{
return m_priority_queue.front();
}
const T& top() const
{
return m_priority_queue.front();
}
bool empty() const
{
return m_priority_queue.empty();
}
private:
Container m_priority_queue;
Compare c;
};
}