STL Heap使用方法

概述

STL中的heap并不是container，默认是最大堆，如果需要最小堆，则需要添加参数greater<type>()
常用堆操作：make_heap(), pop_heap(), push_heap(), sort_heap(), 头文件<algorithm>
1.make_heap(v.begin(), v.end())使序列变成堆
2.push_heap(v.begin(),v.end())假设[first, last-1)有序，新添加元素进堆，需要配合push_back()
3.pop_heap(v.begin(),v.end()) 并不是真正的弹出元素，而是将first、last调换位置，将[first, last-1)做成，需要配合pop_back()
4.sort_heap() 对container进行堆排序。

// range heap example
#include <iostream>     // std::cout
#include <algorithm>    // std::make_heap, std::pop_heap, std::push_heap, std::sort_heap
#include <vector>       // std::vector

int main () {
  int myints[] = {10,20,30,5,15};
  std::vector<int> v(myints,myints+5);

  std::make_heap (v.begin(),v.end());
  std::cout << "initial max heap   : " << v.front() << '\n';

  std::pop_heap (v.begin(),v.end()); v.pop_back();
  std::cout << "max heap after pop : " << v.front() << '\n';

  v.push_back(99); std::push_heap (v.begin(),v.end());
  std::cout << "max heap after push: " << v.front() << '\n';

  std::sort_heap (v.begin(),v.end());

  std::cout << "final sorted range :";
  for (unsigned i=0; i<v.size(); i++)
    std::cout << ' ' << v[i];

  std::cout << '\n';

  return 0;
}

输出结果:

initial max heap   : 30
max heap after pop : 20
max heap after push: 99
final sorted range : 5 10 15 20 99