cpp 堆/堆排序

Posted 2022-11-28 顾文繁

https://www.cnblogs.com/jingmoxukong/p/4303826.html
首先应该先了解堆的基础知识。
再向下调整或者向上调整时，要明确的几个点。
设当前元素在数组中以R[i]表示，那么，
(1) 它的左孩子结点是：R[2i+1];
(2) 它的右孩子结点是：R[2i+2];
(3) 它的父结点是：R[(i-1)/2];
本质是对一颗完全二叉树的操作。

#pragma once
#include <iostream>
#include <vector>
using namespace std;
class BigHeap

public:
	bool operator()()
	
		return true;
	
;
class SmallHeap

public:
	bool operator()()
	
		return true;
	
;

template<class T, class BigOrSmall>
class Heap

public:
	std::vector<T> array_;
	BigOrSmall big_heap_;
	Heap(int* arr, size_t size)
	
		for (int i = 0; i < size; i++)
		
			array_.push_back(arr[i]);
		
		//自底向上，构建堆，向上调整
		for (int i = (array_.size() - 2) / 2; i >= 0; i--)
		
			AdjustDown(i);
		
		cout << endl;
		for (int i = 0; i < size; i++)
		
			cout << array_[i] << " ";
		
	
	void Push(T data)
	
		array_.push_back(T);
		AdjustUp(array_.size() - 1);

	
	T Pop()
	
		swap(array_[0], array_[array_.size() - 1]);
		T tmp = array_[array_.size() - 1];
		array_.pop_back();
		AdjustDown(0);
		cout << endl;
		return tmp;
	
	void HeapSort()
	
		int i = 0;
		if (big_heap_())
		
			while (i < array_.size() - 1)
			
				if (array_[i] < array_[i + 1])
					swap(array_[i], array_[i+1]);
				AdjustDown(i);
				++i;
			
		
		else
		
			while (i < array_.size() - 1)
			
				if (array_[i] > array_[i + 1])
					swap(array_[i], array_[i + 1]);
				AdjustDown(i);
				++i;
			
		
	
protected:
	
	void AdjustDown(size_t index)
	
		while (index < array_.size() - 1)
		
			//大根堆，array[0]为最大值
			if (big_heap_())
			
				//调整左右孩子,使得右边孩子大于左孩子
				if ((index * 2 + 2) < array_.size() && array_[index * 2 + 1] < array_[index * 2 + 2])
				
					swap(array_[index * 2 + 2], array_[index * 2 + 1]);
				
				//调整父子，使得父节点大于左孩子
				if ((index * 2 + 1) < array_.size() && array_[index * 2 + 1] > array_[index])
				
					swap(array_[index], array_[index * 2 + 1]);
				

			
			//小根堆
			else
			
				//调整左右孩子,使得右边孩子小于左孩子
				if ((index * 2 + 2) < array_.size() - 2 && array_[index * 2 + 1] > array_[index * 2 + 2])
				
					swap(array_[index * 2 + 2], array_[index * 2 + 1]);
				
				//调整父子，使得父节点小于左孩子
				if ((index * 2 + 1) < array_.size() - 2 && array_[index * 2 + 1] < array_[index])
				
					swap(array_[index], array_[index * 2 + 1]);
				
			
			index = index * 2 + 1;
		
	
	void AdjustUp(size_t index)
	
		while (index != 0)
		
			size_t i = (index - 1) / 2;
			//仿函数
			if (big_heap_())
			
				if (index + 1 < array_.size() && array_[index + 1] > array_[index])
					swap(array_[index + 1], array_[index]);
				if (array_[i] < array_[index])
					swap(array_[index], array_[i]);
				else
					break;//当前节点已经大于了子节点不用再调整堆了
			
			else
			
				if (index + 1 < array_.size() && array_[index + 1] < array_[index])
					swap(array_[index + 1], array_[index]);
				if (array_[i] > array_[index])
					swap(array_[index], array_[i]);
				else
					break;
			
			index = i;
		
	

	
private:
	Heap() 
;