趣解堆排序--老子儿子争王位

/*
The MIT License (MIT)

Copyright (c) <2014> <oliver-lxtech2013@gmail.com>

Permission is hereby granted, free of charge, to any person obtaining a copy
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furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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THE SOFTWARE.
*/

#include "HeapSort.h"

HeapSortArray::HeapSortArray()
{
//ctor
}

HeapSortArray::~HeapSortArray()
{
//dtor
}

/*
* [public]建立最大堆
* @param a 堆化数组
*/
void HeapSortArray::buildMaxHeap(vector<int> &a) {
int len = a.size();
int i;                 //倒数第一个非叶子节点的下标为n/2 - 1(有孩子的节点为[len/2-1, 0])
for(i = len/2 - 1; i >= 0; i--) {
maxHeapify(a, i, len);
}
}

/*
* [public]维护最大堆性质
* @param a 堆化数组
* @param index Root节点下标
* @param heap_size 调整的树长度
*/
void HeapSortArray::maxHeapify(vector<int> &a, int root, int heap_size) {
int l = 2 * root + 1;        //左孩子,如果下标从0开始,Left(root) = 2 * root + 1;
int r = l + 1;               //右孩子
int largest = root;          //首先老子认为老子自个的兵是最多的

/* 左边的孩子跟老子比兵权大小(记得先看看自个左边有没有孩子) */
if(l <= heap_size - 1 && a[l] > a[largest]) {
largest = l;             //我去,左边孩子的兵居然比我多,好吧,王位暂时让给你了.
}
/* 右孩子也要参与比多(记得看看右边有没有生孩子) */
if(r <= heap_size - 1 && a[r] > a[largest]) {
largest = r;             //我去,右边孩子又想和最多兵的人比比,好吧,右边孩子比较多，王位让给你.
}
/*
* 如果老子我不是最大的,那没办法,最顶上的王位
* 要拱手让给最大的儿子
*/
if(largest != root) {
_swap(&a[root], &a[largest]);         //这会，得和有最多兵的儿子换个位子
maxHeapify(a, largest, heap_size);    //换到大儿子家,妈呀,还得看有没有打破儿子家的平衡,和孙子比比(交换后largest处大顶堆可能破坏,递归重新排)
}
}

/*
* [public]排序
*/
void HeapSortArray::Sort() {
/* 构建大顶堆 */
int heap_size = this->_sortArray.size();    //数据长度
buildMaxHeap(this->_sortArray);             //建立大顶堆
int i;
for(i = heap_size - 1; i > 0; i--) {
_swap(&this->_sortArray[i], &this->_sortArray[0]);    //交换,冒出最大Root
maxHeapify(this->_sortArray, 0, i);                   //交换完后重新调整大顶堆
}

}

/*
* [public]添加一个元素到末尾
* @param a 要添加的元素
* @retval none
*/
void HeapSortArray::Add(int a) {
this->_sortArray.push_back(a);
}

/*
* [private]获取某个数
* @param a 要交换数的a的地址
* @param b 要交换的数b的地址
*/
int HeapSortArray::Get(int index) {
return this->_sortArray[index];
}

/*
* [public]获取此序列里元素的个数
* @param a 要交换数的a的地址
* @param b 要交换的数b的地址
*/
int HeapSortArray::Length() {
return this->_sortArray.size();
}

/*
* [public]打印数组
*/
void HeapSortArray::Printf() {
int i = 0;
cout<<"Array:"<<endl;
for(; i < this->_sortArray.size(); i++) {
cout<<"A"<<i<<":"<<this->_sortArray[i]<<endl;
}
}

/*
* [private]交换两个数
* @param a 要交换数的a的地址
* @param b 要交换的数b的地址
*/
void HeapSortArray::_swap(int* a, int* b) {
//如果两个地址相同,则不做交换
if(a == b) return;

int mid = *a;
*a = *b;
*b = mid;
}

转载于:https://www.cnblogs.com/openIoT/p/4108539.html