The C++ Standard Library consists of the header, <algorithm> which defines a collection of functions (principally designed to deal with a range of elements). is_heap_until() is a method in the STL that returns an iterator to the first element in the range which is not in heap order.
Syntax:
is_heap_until( iterator_begin, iterator_end, comparator ); //comparator is optional
Parameters: The is_heap_until() method accepts 3 parameters
- iterator_begin: Iterator to the initial position of container
- iterator_end: Iterator to the final position of container ( Note: the range is [iterator_begin,iterator_end) )
- comparator: Binary function that accepts two elements in the range as arguments, and returns a value convertible to bool.
Return value: iterator to the first element in the range which is not in heap order
Example of is_heap_until() method
#include<iostream>
#include<algorithm>
#include<vector>
using namespace std;
int main()
{
vector<int> v;
v.push_back(4);
v.push_back(3);
v.push_back(8);
v.push_back(-5);
v.push_back(7);
v.push_back(2);
v.push_back(9);
make_heap(v.begin(), v.begin()+4);
auto it = is_heap_until(v.begin(), v.end());
cout<<"The first index that's not part of heap is: "<<distance(v.begin(), it)<<endl;
cout<<"The first element that's not part of heap is: "<< *it;
}
Output:
The first index that's not part of heap is: 4 The first element that's not part of heap is: 7
