标签:输出 nbsp enqueue item com boolean rgs static iterator
代码实现:
//1.3.29 package com.qiusongde.linkedlist; import java.util.Iterator; import java.util.NoSuchElementException; import edu.princeton.cs.algs4.StdIn; import edu.princeton.cs.algs4.StdOut; public class CircularQueue<Item> implements Iterable<Item> { private Node last; private int n; private class Node { Item item; Node next; } public CircularQueue() { last = null; n = 0; } public boolean isEmpty() { return last == null; } public int size() { return n; } public void enqueue(Item item) { Node oldlast = last;//save oldlast last = new Node();//new node last.item = item; if(oldlast == null) {//empty last.next = last; } else { last.next = oldlast.next;//next is first oldlast.next = last; } n++; } public Item dequeue() { if(isEmpty()) throw new NoSuchElementException("Queue is empty"); Item item = last.next.item; if(last.next == last) {//only one node last = null; } else { last.next = last.next.next; } n--; return item; } @Override public Iterator<Item> iterator() { return new CircularQueueIterator(); } private class CircularQueueIterator implements Iterator<Item> { //it is important that this class cannot change the CircularQueue //so we can only change precurrent and can‘t change precurrent.next private Node precurrent; public CircularQueueIterator() { precurrent = last; } @Override public boolean hasNext() { return precurrent != null; } @Override public Item next() { if(!hasNext()) throw new NoSuchElementException("Queue is empty"); Item item = precurrent.next.item; if(last == last.next) {//one node precurrent = null;//end } else { precurrent = precurrent.next; if(precurrent == last) {//precurrent equals last again precurrent = null;//end } } return item; } @Override public void remove() { throw new UnsupportedOperationException(); } } public static void main(String[] args) { CircularQueue<String> queue = new CircularQueue<String>(); StdOut.println("Initialized size:" + queue.size()); while (!StdIn.isEmpty()) { String item = StdIn.readString(); if (!item.equals("-")) { queue.enqueue(item); StdOut.println("enqueue success:" + item + " size:" + queue.size()); StdOut.print("Left on queue: "); for (String s : queue) { StdOut.print(s + " "); } StdOut.println(); } else { if(queue.isEmpty()) StdOut.println("dequeue error, queue empty"); else { StdOut.println("dequeue success:" + queue.dequeue() + " size:" + queue.size()); StdOut.print("Left on queue: "); for (String s : queue) { StdOut.print(s + " "); } StdOut.println(); } } } } }
测试数据;
to be or not to - be - - that - - - is
输出结果:
Initialized size:0 enqueue success:to size:1 Left on queue: to enqueue success:be size:2 Left on queue: to be enqueue success:or size:3 Left on queue: to be or enqueue success:not size:4 Left on queue: to be or not enqueue success:to size:5 Left on queue: to be or not to dequeue success:to size:4 Left on queue: be or not to enqueue success:be size:5 Left on queue: be or not to be dequeue success:be size:4 Left on queue: or not to be dequeue success:or size:3 Left on queue: not to be enqueue success:that size:4 Left on queue: not to be that dequeue success:not size:3 Left on queue: to be that dequeue success:to size:2 Left on queue: be that dequeue success:be size:1 Left on queue: that enqueue success:is size:2 Left on queue: that is
标签:输出 nbsp enqueue item com boolean rgs static iterator
原文地址:http://www.cnblogs.com/songdechiu/p/6511595.html