鏈表實現(xiàn)隊列：

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鏈表隊列的實現(xiàn)：

package com.lt.datastructure.Queue;public class LinkedListQueue<E> implements Queue<E>{ public class Node{public E e;public Node next;public Node(E e,Node next){this.e = e;this.next = next;}public Node(E e){this(e,null);}public Node(){this(null,null);}@Overridepublic String toString() {return e.toString();}}private Node head,tail;private int size;public LinkedListQueue() {head = null;tail = null;size = 0;}@Overridepublic int getSize() {return size;}@Overridepublic boolean isEmpty() {return size==0;}/** 入隊 * 如果tail尾結(jié)點是空,新建第一個結(jié)點，head和tail指向此結(jié)點* 如果tail不為空,在tail的下一個位置新建結(jié)點,當(dāng)作尾結(jié)點*/@Overridepublic void enqueue(E e) {if(tail==null){tail = new Node(e);head = tail;}else{tail.next = new Node(e);tail = tail.next;}size ++;}@Override/** 出隊* 首先判斷能不能出隊，判斷是否為空* 不為空，則刪除頭結(jié)點*/public E dequeue() {if(isEmpty()){throw new IllegalArgumentException("Cannot dequeue from a Empty queue.");}//retNode指向headNode retNode = head;//head后移，為刪除做準(zhǔn)備head = head.next;//刪除retNoderetNode.next = null;//如果只有一個結(jié)點，刪除之后讓tail為空if(head == null) {tail =null;}size --;return retNode.e;}@Overridepublic E getFront(E e) {if(isEmpty()){throw new IllegalArgumentException("Queue is empty.");}return head.e;}@Overridepublic String toString() {StringBuilder res = new StringBuilder();res.append("Queue:front ");Node cur = head;while(cur != null){res.append(cur +"->");cur = cur.next;}res.append("null");return res.toString();}public static void main(String[] args) {LinkedListQueue<Integer> queue = new LinkedListQueue<>();for(int i =0; i<10; i++){queue.enqueue(i);System.out.println(queue);if(i%3==2){queue.dequeue();System.out.println(queue); }}}}

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測試：

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復(fù)雜度測試：

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package com.lt.datastructure.Queue;import java.util.Random;public class Main {/** 測試ArrayQueue和LoopQueue*/private static double testQueue(Queue<Integer> q , int opCount){long startTime = System.nanoTime();//..Random random = new Random();for(int i =0; i<opCount;i++){q.enqueue(random.nextInt(Integer.MAX_VALUE));}for(int i=0; i<opCount; i++){q.dequeue();}long endTime = System.nanoTime();return (endTime-startTime)/1000000000.0;} public static void main(String[] args){int opCount = 100000;ArrayQueue<Integer> arrayQueue = new ArrayQueue<>();System.out.println("ArrayQueue:"+testQueue(arrayQueue,opCount));LoopQueue<Integer> loopQueue = new LoopQueue<>();System.out.println("LoopQueue:"+testQueue(loopQueue, opCount));LinkedListQueue<Integer> linkedListQueue = new LinkedListQueue<>();System.out.println("LinkedListQueue:"+testQueue(linkedListQueue, opCount));} }

三種隊列分別所需時間：

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轉(zhuǎn)載于:https://www.cnblogs.com/ltfxy/p/9987739.html

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