scranton.queue
Interface PriorityQueue

All Known Implementing Classes:

PriorityQueueViaHeapArray

public interface PriorityQueue

A priority queue applies a comparator so that the remove method dispenses the object that preceed the other objects in the queue when odered with the comparator. Initial condition: this = (); If this = (a₀, a₁, ..., a_n-1) then a₀ is the front object and a_n-1 is the rear object. and there is an order relationship "<=" such that a_i <= a_i+1 for all i, 0<=i<#(L)-2

Method Summary

java.lang.Object	frontOf() Method frontOf return front, a0.
void	insert(java.lang.Object item) Method insert item into the PriorityQueue.
boolean	isEmpty() Method isEmpty returns this==().
java.lang.Object	remove() Method remove the object from the front of the PriorityQueue, a0.

Method Detail

isEmpty

public boolean isEmpty()

Method isEmpty returns this==(). this'=this .

Returns:

boolean

frontOf

public java.lang.Object frontOf()

Method frontOf return front, a₀. pre: this /= () this'=this

Returns:

Object

insert

public void insert(java.lang.Object item)

Method insert item into the PriorityQueue.

Parameters:

item - Post: i'=#(this)+1 There is a k such that a'_k=item and

remove

public java.lang.Object remove()

Method remove the object from the front of the PriorityQueue, a₀.

Returns:

Object pre: this /= (), post: this = (a₀, this')