- <init>
Constructor. Default use a 3-heap.
- empty
Returns true if the queue is empty.
- insert
Insert a new item into queue.
- less
Priority comparison of item i and j.
- lower
The value of item k is lower (higher priority) now.
- poll
Removes and returns the index of item with minimum value (highest priority).
- swap
Swap i and j items of pq and qp.
- swim
fix up.