The MaxPQ class represents a priority queue of generic keys. It supports the usual Insert and Delete-the-maximum operations, along with methods for peeking at the maximum key, testing if the priority queue is empty, and iterating through the keys.

This implementation uses a binary heap. The Insert and Delete-the-maximum operations take logarithmic amortized time. The Max, Count, and IsEmpty operations take constant time. Construction takes time proportional to the specified capacity or the number of items used to initialize the data structure.