堆（算法导论 part1 foundations, chapter 6 heapsort）

最新推荐文章于 2025-07-31 22:28:05 发布

liulin063326

最新推荐文章于 2025-07-31 22:28:05 发布

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文章标签：算法 iterator build join ini

本文链接：https://blog.youkuaiyun.com/liulin063326/article/details/7885798

本文介绍了一种使用C++实现的堆排序算法，包括初始化数组、构建最大堆、堆排序过程及最终排序结果展示。

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#include<iostream>
#include<time.h>
using namespace std;

const int AD = 6;
int arr[AD];

void initializeArray(int arr[], int n){
srand(time(0));
for(int i=0;i<n;i++){
arr[i] = rand()%400;
}
}

void swap(int& a, int&b){
int temp = a;
a = b;
b = temp;
}

void printArray(int arr[], int n){
for(int i=0; i<n; i++){
cout<<arr[i]<<" ";
}
cout<<endl;
}

//left, right are max heap, join arr[index] in
void max_heapify_recursive(int arr[], int heapSize, int index){
int left = (index <<1) +1;
int right = (index<<1) +2;
int largest = index;
if(left<heapSize && arr[left]>arr[index]){
  largest = left;
}if(right<heapSize && arr[right] > arr[largest]){
  largest = right;
}
if(largest != index){
  swap(arr[largest],arr[index]);
  max_heapify_recursive(arr,heapSize,largest);
}
}

void max_heapify_iterator(int arr[], int heapSize, int index){
int left = (index<<1)+1;
int right = (index<<1) +2;
int largest = index;
while(left<heapSize){// has child
  if(left<heapSize && arr[left] > arr[index]){
   largest = left;
  }if(right<heapSize && arr[right] > arr[largest]){
   largest = right;
  }
  if(largest == index){
   break;
  }else{
   swap(arr[index],arr[largest]);
   index = largest;
   left = (index<<1)+1;
   right = (index<<1)+2;
   largest = index;
  }

}
}
//max_heapify downward from the first internal node to 0
void build_max_heap(int arr[], int n){
for(int i= n/2-1; i>=0; i--){
max_heapify_iterator(arr,n,i);
}
}

void heapSort(int arr[], int n){
build_max_heap(arr,n);
int heapSize = n;
for(int i=n-1; i>0; i--){
swap(arr[i],arr[0]);
max_heapify_iterator(arr,--heapSize,0);

}
}
void main(){
initializeArray(arr,AD);
printArray(arr,AD);

//build_max_heap(arr,AD);
heapSort(arr,AD);
printArray(arr,AD);
}

共同进步