用非顺序映像实现队列 

 1 package myqueue;
 2 
 3 import mylinkedlist.MyLinkedList;
 4 
 5 import java.util.NoSuchElementException;
 6 
 7 public class myQueue <E>{
 8     private Node head;
 9     private Node end;
10     private int size;
11 
12     private static class Node<E>{
13         public Node next;
14         public Node prev;
15         E val;
16         public Node(E val){
17             this.val = val;
18         }
19         public Node(Node prev,E val,Node next){
20             this.val = val;
21             this.next = next;
22             this.prev = prev;
23         }
24     }
25 
26     public myQueue(){
27         head = new Node(null);
28         end = new Node(null);
29         head.next = end;
30         end.prev = head;
31 
32     }
33     public void enque(E e){
34         Node nodeToEnque = new Node(end.prev,e,end);
35         end.prev.next = nodeToEnque;
36         end.prev = nodeToEnque;
37         size++;
38     }
39     public E deque(){
40         //先判断是否队空
41         if(isEmpty()){
42             throw new NoSuchElementException();
43         }
44         Node nodeToRemove = head.next;
45         head.next = head.next.next;
46         nodeToRemove.next.prev = head;
47         size--;
48         return (E)nodeToRemove.val;
49 
50     }
51 
52     public boolean isEmpty() {
53         return size==0;
54     }
55     public int size(){
56         return size;
57     }
58     public E peek(){
59         return (E)head.next.val;
60     }
61     public String toString(){
62         StringBuilder sb = new StringBuilder("[");
63         Node x =head.next;
64         while(x!=end){
65             sb.append(x.val).append(", ");
66             x =x.next;
67         }
68         if(size !=0) sb.delete(sb.length()-2,sb.length());
69         return sb.append("]").toString();
70     }
71 
72 }
 1 package myqueue;
 2 
 3 public class TestMyQueue {
 4     public static void main(String args[]){
 5         myQueue<Integer> que = new myQueue();
 6         System.out.println("队列空吗？"+que.isEmpty());
 7         que.enque(1);
 8         que.enque(2);
 9         que.enque(3);
10         que.enque(4);
11         System.out.println(que.toString()+"，长度位："+que.size());
12         System.out.println("出队："+que.deque());
13         System.out.println("队列空吗？"+que.isEmpty());
14 
15 
16     }
17 }

 

posted @ 2020-07-18 00:58  JC97  阅读(294)  评论(0)    收藏  举报