#include <algorithm>
  void make_heap( iterator start, iterator end );
  void make_heap( iterator start, iterator end, StrictWeakOrdering cmp );

The make_heap() function turns the given range of elements [start,end) into a heap.

If the strict weak ordering comparison function object cmp is given, then it is used instead of the < operator to compare elements.

make_heap() runs in linear time.