反转单链表和双向链表

 1 package my_basic.class_3;
 2 
 3 public class Code_07_ReverseList {
 4     public static class Node{
 5         private int value;
 6         private Node next;
 7         
 8         public Node(int value) {
 9             super();
10             this.value = value;
11         }
12     }
13     
14     /*反转单向链表*/
15     public static Node reverseList(Node head) {
16         Node next = null;
17         Node pre = null;
18         while (head != null) {
19             next = head.next;
20             head.next = pre;
21             pre = head;
22             head = next;
23         }
24         return pre;
25     }
26     
27     public static class DoubleNode{
28         private int value;
29         private DoubleNode next;
30         private DoubleNode last;
31         public DoubleNode(int value) {
32             super();
33             this.value = value;
34         }
35     }
36     
37     public static DoubleNode reverseList(DoubleNode head) {
38         DoubleNode next = null;
39         DoubleNode pre = null;
40         while (head != null) {
41             next =head.next;
42             head.next = pre;
43             head.last = next;
44             pre = head;
45             head = next;
46         }
47         return pre;
48     }
49     
50     public static void printLinkedList(Node head) {
51         System.out.println("单链表：");
52         while(head != null) {
53             System.out.print(head.value + " ");
54             head = head.next;
55         }
56         System.out.println();
57     }
58     
59     public static void printDoubleLinkedList(DoubleNode head) {
60         System.out.println("双向单链表：");
61         DoubleNode end = null;
62         while (head != null) {
63             System.out.print(head.value + " ");
64             end = head;
65             head = head.next;
66         }
67         System.out.println("|");
68         while (end != null) {
69             System.out.print(end.value + " ");
70             end = end.last;
71         }
72         System.out.println();
73         
74     }
75     
76     public static void main(String[] args) {
77         Node head1 = new Node(1);
78         head1.next = new Node(2);
79         head1.next.next = new Node(3);
80         printLinkedList(head1);
81         head1 = reverseList(head1);
82         printLinkedList(head1);
83 
84         DoubleNode head2 = new DoubleNode(1);
85         head2.next = new DoubleNode(2);
86         head2.next.last = head2;
87         head2.next.next = new DoubleNode(3);
88         head2.next.next.last = head2.next;
89         head2.next.next.next = new DoubleNode(4);
90         head2.next.next.next.last = head2.next.next;
91         printDoubleLinkedList(head2);
92         printDoubleLinkedList(reverseList(head2));
93 
94     }
95 
96 }