class PriorityQueue {
       
      private int  count;       // the number of items in the priority queue
      private int  capacity;      // the number of available array positions
      private int  capacityIncrement; // the amount to increase the capacity
                                                   // during array expansion
      private ComparisonKey[] itemArray;    // the array that holds PQ items
       
      /*-----------------*/
    
      /** construct an initially empty PriorityQueue */
       
      public PriorityQueue() {    // we need to define a no-arg constructor.
         count = 0;                  // the empty priority queue has no items
         capacity = 10;                // but there is capacity for ten items
         capacityIncrement = 5;               // and the capacity will expand
         itemArray = new ComparisonKey[capacity];    // in increments of five
      }                                                    // when necessary
       
      /*-----------------*/
       
      /** the size() method returns the count of the number of items */
       
      public int size() {
         return count;
      }
       
      /*-----------------*/
     
      /** the insert() method inserts a new item into a priority queue */
       
      public void insert(ComparisonKey newItem) {
         
         // if the itemArray does not have enough capacity,
         // expand the itemArray by the capacity increment
         if (count == capacity) {
            capacity += capacityIncrement;
            ComparisonKey[] tempArray = new ComparisonKey[capacity];
            for (int i = 0; i < count; i++) {
               tempArray[i] = itemArray[i];
            }
            itemArray = tempArray;
         }
         
         // insert the newItem at the end of the current sequence of items
         // and increase the priority queue's count by one
         itemArray[count++] = newItem;
      }
     
      /*-----------------*/
    
      /** the remove() method removes the highest priority item */
       
      public ComparisonKey remove() {
      if (count == 0) {                     // return null if the priority
         return null;                                    // queue is empty.
      } else {                     // otherwise, find the highest priority
         int maxPosition = 0;                            // item's position
         ComparisonKey maxItem = itemArray[0];
         for (int i = 1; i < count; i++) {
            if ( itemArray[i].compareTo(maxItem) > 0 ) {
               maxPosition = i;
               maxItem = itemArray[i];
            }                               // then move the last item into
         }                                           // the hole created by
         itemArray[maxPosition] = itemArray[--count];       // removing the
         return maxItem;                           // highest priority item
      }                           // and, return the highest priority item
   }