Free implementation of “bounded priority queue” in C++

Question

I'm looking for a free software implementation of the bounded priority queue abstraction in C++. Basically, I need a data structure that will behave just like std::priority_queue but will at all times hold the "best" n elements at most.

Example:

std::vector<int> items; // many many input items
bounded_priority_queue<int> smallest_items(5);
for(vector<int>::const_iterator it=items.begin(); it!=items.end(); it++) {
  smallest_items.push(*it);
}
// now smallest_items holds the 5 smallest integers from the input vector

Does anyone know of a good implementation of such thing? Any experience with it?

Answer 1

I think that the algorithm discussed in this thread is probably what you are looking for. If you want to get a head start, you might want to consider building upon Boost's implementation d_ary_heap_indirect which is part of Boost.Graph (in d_ary_heap.hpp ). If you do a good job with it, you might submit it to Boost. It could make a nice little addition, because such an implementation certainly has many uses.

Answer 2

Why not use a std::vector with a functor/comparison function and std::sort() it into the correct order? The code is probably pretty trivial