How to tell a std::priority_queue to refresh its ordering?

Question

I have a priority queue of pointers to a struct city. I modify the objects pointed by these pointers outside the priority queue, and want to tell the priority q

Answer 1

This is a bit hackish, but nothing illegal about it, and it gets the job done.

std::make_heap(const_cast(&cities.top()),
               const_cast(&cities.top()) + cities.size(),
               Compare());

Update:

Do not use this hack if:

• The underlying container is not vector.
• The Compare functor has behavior that would cause your external copy to order differently than the copy of Compare stored inside the priority_queue.
• You don't fully understand what these warnings mean.

You can always write your own container adaptor which wraps the heap algorithms. priority_queue is nothing but a simple wrapper around make/push/pop_heap.