queue.h

图论：最短路径算法实现 Graph.gph GraphBFS.h GraphM.h GraphOpr.h Queue.h sample.gph ShortPth.cpp ShortPt

#ifndef QUEUE_H
#define QUEUE_H

template <class Elem> class Queue
{
private:
  int size;                  // Maximum size of queue
  int front;                 // Index of front element
  int rear;                  // Index of rear element
  Elem *listArray;           // Array holding queue elements
public:
  Queue(int sz =DefaultListSize) { // Constructor 
    // Make list array one position larger for empty slot
    size = sz+1;
    rear = 0;  front = 1;
    listArray = new Elem[size];
  }
  ~Queue() { delete [] listArray; } // Destructor
  void clear() { front = rear; }
  bool enqueue(const Elem& it) {
    if (((rear+2) % size) == front) return false;  // Full
    rear = (rear+1) % size; // Circular increment
    listArray[rear] = it;
    return true;
  }
  bool dequeue(Elem& it) {
    if (length() == 0) return false;  // Empty
    it = listArray[front];
    front = (front+1) % size; // Circular increment
    return true;
  }
  bool frontValue(Elem& it) const {
    if (length() == 0) return false;  // Empty
    it = listArray[front];
    return true;
  }
  virtual int length() const
   { return ((rear+size) - front + 1) % size; }
};

#endif