C++堆排序算法实例详解

#include<iostream>int heapsize=0;//全局变量记录堆的大小void heapSort(int array[],int n){ void buildHeap(int [],int); void exchange(int[],int,int); void heapify(int[],int); buildHeap(array,n); for(int i=n-1;i>=1;i--){  exchange(array,0,i);  heapsize--;  heapify(array,0); }}//构建堆void buildHeap(int array[],int n){ void heapify(int[],int); heapsize=n; //从最小的父节点开始，进行堆化，直到树根节点 for(int i=heapsize/2-1;i>=0;i--){  heapify(array,i); }}//堆化void heapify(int array[],int n){ void exchange(int[],int,int); int left_child=n*2+1; int right_child=n*2+2; int largest; if(left_child<heapsize&&array[left_child]>array[n]){  largest = left_child; } else{  largest = n; } if(right_child<heapsize&&array[right_child]>array[largest]){  largest=right_child; } if(largest!=n){  exchange(array,largest,n);  heapify(array,largest); }}void exchange(int array[],int i,int j){ int tmp = array[i]; array[i]=array[j]; array[j]=tmp;}int main(){  int arr[9]={3,1,6,9,8,2,4,7,5};  heapSort(arr,9);  for(int i=0;i<9;++i){    std::cout<<arr[i]<<" ";  }  std::cout<<std::endl;  return 0;}STL中实现了max-heap的操作。在使用heap算法是需添加头文件algorithm。#include <iostream>#include<vector>#include<algorithm>int main(){  int arr[9]={0,1,2,3,4,8,9,3,5};  std::vector<int> vec(arr,arr+9);  //0 1 2 3 4 8 9 3 5  for(auto c:vec){    std::cout<<c<<" ";  }  std::cout<<std::endl;  make_heap(vec.begin(),vec.end());  //9 5 8 3 4 0 2 3 1  for(auto c:vec){    std::cout<<c<<" ";  }  std::cout<<std::endl;  vec.push_back(7);  push_heap(vec.begin(),vec.end());  //9 7 8 3 5 0 2 3 1 4  for(auto c:vec){    std::cout<<c<<" ";  }  std::cout<<std::endl;  pop_heap(vec.begin(),vec.end());  //8 7 4 3 5 0 2 3 1 9,只是将最大值挪到了vector的最后，并没有删除  for(auto c:vec){    std::cout<<c<<" ";  }  std::cout<<std::endl;  std::cout<<vec.back()<<std::endl;//9  //将9删除  vec.pop_back();  //连续的pop_heap操作，每次的最大值都放在最尾端，最后呈现递增排序  sort_heap(vec.begin(),vec.end());  //0 1 2 3 3 4 5 7 8  for(auto c:vec){    std::cout<<c<<" ";  }  std::cout<<std::endl;  return 0;}