The reason of using `std::greater` for creating min heap via `priority_queue`

Question

I am wondering why for creating a min heap using the priority_queue, the std::greater should be used?

std::priority_queue

        

Answer 1

See http://en.cppreference.com/w/cpp/container/priority_queue. A priority_queue is designed to put the largest value at the top. This happens if you use the default std::less comparator. So if you want the reverse behavior, you need to use the reverse comparator, std::greater.