template<class RanIt>
void pop_heap(RanIt first, RanIt last);
template<class RanIt, class Pred>
void pop_heap(RanIt first, RanIt last, Pred pr);
The first template function reorders the sequence designated by iterators in the range [first, last) to form a new
heap, ordered by operator< and designated by iterators in the range [first, last - 1), leaving the original
element at *first subsequently at *(last - 1). The original sequence must designate an existing heap, also ordered
by operator<. Thus, first != last must be true and *(last - 1) is the element to remove from (pop off) the
heap.
The function evaluates the ordering predicate X < Y ceil(2 * log(last - first)) times, at most.
The second template function behaves the same, except that it replaces operator<(X, Y) with pr(X, Y).
Sample programs: heap and heap (predicate version).