#ifndef _TPQUEUE_H
#define _TPQUEUE_H

// templated priority queue class
// written and modified thousands of times
// the last time was 11/27/95 for cps 100, fall 1995
// to use vector class rather than array type
//
// operations:
//
// PQueue(int)
//     construct pqueue of specified size
//
// void Insert(const Kind &, int)
//     insert Kind object with specified
//     integer priority
//
// int NumElts() const
//     returns the number of elements in the priority queue
//
// bool IsEmpty() const
//     returns true if pqueue is empty, otherwise returns false
//
// void DeleteMin()
//     remove minimal element from queue
//
// void MinElt(Kind &, int &)
//     return minimal element and its integer priority
//
// Complexity:
//
// a heap-based implementation is used, so MinElt is O(1)
// and Insert/DeleteMin are O(log n) where n is # of items in pqueue

#include "vector.h"

template <class Kind> class PQueue
{
  public:
    PQueue(int);                         // initialize to given size
    ~PQueue();
    void Insert(const Kind &,int);       // insert kind with int priority
    int NumElts() const;                 // return # of elements in queue
    bool IsEmpty() const;                // return true iff empty
    void DeleteMin();                    // remove min elt from pqueue
    void MinElt(Kind &,int &);           // return min elt and priority
  private:
    struct Qelt
    {
	Kind thing;                      // item stored in pqueue
	int priority;                    // priority of the item
    };
    void Heapify(int vroot);             // percolate down function
    Vector<Qelt> myList;                 // array of prioritized stuff
    int myNumElts;                       // # elements in priority queue
};

// uncomment line below if including source code (no template.cc)
// #include "tpqueue.cc"

#endif