Why sir has not use priority_queue

#1

As in 5:30 sir has told we will come to reason not use priority queue but not told it in end also;

I want to know as in Priority Queue we pop in O(1) ans insert element in O(longN).

#2

there is no solid reason to not use priority queue
you can use both priority_queue and set here

yes set has a advantage over priority_queue
that in set you can access all element but in priority queue only top element is accessible

yes
std::priority_queue allows to do the following:

  1. Insert an element O(log n)
  2. Get the smallest element O(1)
  3. Erase the smallest element O(log n)

while std::set has more possibilities:

  1. Insert any element O(log n) and the constant is greater than in std::priority_queue
  2. Find any element O(log n)
  3. Find an element, >= than the one your are looking for O(log n) ( lower_bound )
  4. Erase any element O(log n)
  5. Erase any element by its iterator O(1)
  6. Move to previous/next element in sorted order O(1)
  7. Get the smallest element O(1)
  8. Get the largest element O(1)