title: Double ended priority queue
body: <p>I have a set of data and I want to find the biggest and smallest items (multiple times), what's the best way to do this?</p>
  
  <p>For anyone interested in the application, I'm developing a level of detail system and I need to find the items with the biggest and smallest screen space error, obviously every time I subdivide/merge an item I have to insert it into the queue but every time the camera moves the entire dataset changes - so it might be best to just use a sorted list and defer adding new items until the next time I sort (since it happens so often)</p>