数据结构之队列

Posted 2020-10-04 宋发准

队列是一种特殊的线性表,特殊之处在于它只允许在表的前端（front）进行删除操作，而在表的后端（rear）进行插入操作，和栈一样，队列是一种操作受限制的线性表。进行插入操作的端称为队尾，进行删除操作的端称为队头。先进先出（FIFO—first in first out）

队列分为普通队列和环形队列

这里说说环形队列

 

 

 

 

 

  1 package song.queue;
  2 
  3 /**
  4  * Created by sfz on 2017/8/25.
  5  */
  6 public class MyQueue {
  7 
  8     private int[] data;
  9 
 10     //队列数组的长度
 11     private int size = 0;
 12     //对头的下标
 13     private int head = 0;
 14     //队尾的下标
 15     private int tail = 0;
 16     //队列实际 的个数
 17     private int queuelen = 0;
 18 
 19     //初始化队列
 20     public MyQueue(int size) {
 21         this.size = size;
 22         data = new int[size];
 23         clearQueue();
 24     }
 25 
 26 
 27     /**
 28      * 清空队列
 29      */
 30     public void clearQueue() {
 31         head = 0;
 32         tail = 0;
 33         queuelen = 0;
 34     }
 35 
 36     /**
 37      * 队列判空
 38      *
 39      * @return
 40      */
 41     public boolean isEmpty() {
 42         return queuelen == 0;
 43     }
 44 
 45     /**
 46      * 实际长度
 47      *
 48      * @return
 49      */
 50     public int queueLength() {
 51         return queuelen;
 52     }
 53 
 54     /**
 55      * 判满
 56      *
 57      * @return
 58      */
 59     public boolean isfull() {
 60         return queuelen == size;
 61     }
 62 
 63     /**
 64      * 入队
 65      *
 66      * @param ele
 67      * @return
 68      */
 69     public boolean enQueue(int ele) {
 70         if (isfull()) {
 71             return false;
 72         } else {
 73             data[tail] = ele;
 74             tail++;
 75             tail = tail % size;
 76             queuelen++;
 77             return true;
 78         }
 79     }
 80 
 81 
 82     /**
 83      * 出对
 84      *
 85      * @param ele
 86      * @return
 87      */
 88     public boolean deQqueue(int ele) {
 89         if (isEmpty()) {
 90             return false;
 91         } else {
 92             data[head] = 0;
 93             head++;
 94             head = head % size;
 95             queuelen--;
 96             return true;
 97         }
 98 
 99 
100     }
101 
102     /**
103      * 遍历
104      */
105     public void traverse() {
106         for (int i = head; i < queuelen+head; i++) {
107             int val = data[i % size];
108             System.out.print(val+ " ");
109         }
110         System.out.println();
111     }
112 
113 }

View Code

 1 package song.queue;
 2 
 3 import org.junit.Test;
 4 import song.tree.Tree;
 5 
 6 /**
 7  * Created by sfz on 2017/8/25.
 8  */
 9 public class Test001 {
10 
11     @Test
12     public void test001() throws Exception {
13 
14         MyQueue myQueue = new MyQueue(4);
15 
16         myQueue.enQueue(10);
17         myQueue.enQueue(20);
18         myQueue.enQueue(30);
19         myQueue.enQueue(40);
20 
21         myQueue.traverse();
22 
23 
24 
25         myQueue.deQqueue(0);
26         myQueue.deQqueue(0);
27         myQueue.traverse();
28 
29 
30 
31 
32         myQueue.enQueue(50);
33         myQueue.enQueue(60);
34         myQueue.traverse();
35 
36         myQueue.clearQueue();
37         myQueue.traverse();
38 
39 
40         myQueue.enQueue(70);
41         myQueue.enQueue(80);
42         myQueue.traverse();
43 
44 
45 
46     }
47 }

View Code