优先队列.txt

一个封装好的优先队列,用C++实现的,已经经过调试,直接用就行

//优先队列   值越小优先级越高

#ifndef PRIORITYQUEUE_CLASS
#define PRIORITYQUEUE_CLASS

#include <iostream.h>
#include <stdlib.h>

// maximum size of the priority queue array
const int MaxPQSize  = 50;

class PQueue
{
    private:
        // priority queue array and count
        int count;
        DataType pqlist[MaxPQSize];

    public:
        // constructor
        PQueue (void);
            
        // priority queue modification operations
        void  PQInsert(const DataType& item);
        DataType PQDelete(void);
        void ClearPQ(void);
        
        // priority queue test methods
        int PQEmpty(void) const;
        int PQFull(void) const;
        int PQLength(void) const;
};

// initialize priority queue count
PQueue::PQueue (void) : count(0)
{}
  
// insert item into the priority queue 
void PQueue::PQInsert (const DataType& item)
{
    // if all elements of pqlist are used, terminate the program
    if (count == MaxPQSize)
    {
        cerr << "Priority queue overflow!" << endl;
        exit(1);
    }
    // place item at the rear of the list and increment count
    pqlist[count] = item;
    count++;
}
                    
// delete an element from the priority queue and return its value
DataType PQueue::PQDelete(void)
{
    DataType min;
    int i, minindex = 0;

    if (count > 0)
    {
        // find the minimum value and its index in pqlist
        min = pqlist[0];    // assume pqlist[0] is the minimum
        
        // visit remaining elments, updating minimum and index
        for (i = 1; i < count; i++)
            if (pqlist[i] < min)
            {
                // new minimum is pqlist[i]. new minindex is i
                min = pqlist[i];
                minindex = i;
            }
        // move rear element to minindex and decrement count
        pqlist[minindex] = pqlist[count-1];
        count--;
    }
    // qlist is empty, terminate the program
    else
    {
        cerr << "Deleting from an empty priority queue!" << endl;
        exit(1);
    }
    // return minimum value 
    return min;
}
                    
// return number of list elements
int PQueue::PQLength(void) const
{
    return count;
}

// test for an empty priority queue
int PQueue::PQEmpty(void) const
{
    return count == 0;
}

// test for a full priority queue
int PQueue::PQFull(void) const
{
    return count == MaxPQSize; 
}
    
// clear the priority queue by resetting count to 0
void PQueue::ClearPQ(void)
{
    count = 0;
}
    
#endif  // PRIORITYQUEUE_CLASS