How to preallocate(reserve) a priority_queue?

Question

How can I preallocate a std::priority_queue with a container of type std::vector?

std::priority_queue

        

Answer 1

In general with C++11 you can write a make_reserved function as below.

#include 
#include 
#include 
#include 

template 
std::vector make_reserved(const std::size_t n)
{
  std::vector v;
  v.reserve(n);
  return v;
}

int main()
{
  using Q = std::priority_queue>;
  auto q = Q(std::less(), make_reserved(100));
  std::cout << q.size() << std::endl;
}