Heap in STL

  HEAP DATA STRUCTURE


#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
int main()
{
vector<int>v1;
  v1.push_back(10);
  v1.push_back(5);
  v1.push_back(8);
  v1.push_back(48);
  v1.push_back(20);
  v1.push_back(6);
  v1.push_back(1);


Making Heap 

make_heap(v1.begin(),v1.end());
This will convert this vector into a heap
cout<<v1.front()<<endl;
Sort Heap -> After this the operation the container is sorted and no longer a Heap
sort_heap(v1.begin(),v1.end());
vector<int>::iterator it ;
for(it=v1.begin();it!=v1.end();it++)
{
cout<<*it<<" ";
}
cout<<endl;
Insert new elements in Heap
push_heap() :- This function is used to insert elements into heap. The size of the heap is increased by 1. New element is placed appropriately in the heap.


 pop_heap() :- This function is used to delete the maximum element of the heap. The size of heap is decreased by 1. The heap elements are reorganized accordingly after this operation.
pop_heap() should be followed by a v1.pop_back()  otherwise it won't actually be popped. Coz pop_heap() just shifts the largest element to the end position . pop_back() reduces the size of the heap by one.
 v1.push_back(50);
     
    // using push_heap() to reorder elements
    push_heap(v1.begin(), v1.end());
     
    // Displaying the maximum element of heap
    // using front()
    cout << "The maximum element of heap after push is : ";
    cout << v1.front() << endl;
     
     // using pop_heap() to delete maximum element
    pop_heap(v1.begin(), v1.end());
    v1.pop_back();
     
    // Displaying the maximum element of heap
    // using front()
    cout << "The maximum element of heap after pop is : ";
    cout << v1.front() << endl;

}

output :
48
1 5 6 8 10 20 48
The maximum element of heap after push is : 50
The maximum element of heap after pop is : 6

is_heap() :- This function is used to check whether the container is heap or not. Generally, in most implementations, the reverse sorted container is considered as heap. Returns true if container is heap else returns false.

  is_heap_until() :- This function returns the iterator to the position till the container is the heap. Generally, in most implementations, the reverse sorted container is considered as heap.