1 package com.baozi.offer;
 2
 3 /**
 4  * @author BaoZi
 5  * @create 2019-07-11-16:14
 6  */
 7 public class Offer13 {
 8     public static void main(String[] args) {
 9         ListNode n1 = new ListNode(1);
10         ListNode n2 = new ListNode(2);
11         ListNode n3 = new ListNode(4);
12         ListNode n4 = new ListNode(6);
13         ListNode n5 = new ListNode(8);
14         ListNode n6 = new ListNode(10);
15         n1.next = n2;
16         n2.next = n3;
17         n3.next = n4;
18         n4.next = n5;
19         n5.next = n6;
20         n6.next = null;
21
22         ListNode l1 = new ListNode(1);
23         ListNode l2 = new ListNode(3);
24         ListNode l3 = new ListNode(5);
25         ListNode l4 = new ListNode(7);
26         ListNode l5 = new ListNode(9);
27         ListNode l6 = new ListNode(11);
28         l1.next = l2;
29         l2.next = l3;
30         l3.next = l4;
31         l4.next = l5;
32         l5.next = l6;
33         l6.next = null;
34         Offer13 offer13 = new Offer13();
35         ListNode merge = offer13.Merge(l1, n1);
36         ListNode temp = merge;
37         while (temp != null) {
38             System.out.print(temp.val + "    ");
39             temp = temp.next;
40         }
41     }
42
43     public ListNode Merge(ListNode list1, ListNode list2) {
44         //首先进行特殊情况的判断，并且只有当两个链表都为空的时候才会返回null
45         if (list1 == null && list2 == null) {
46             return null;
47         }
48         //创建一个新的链表头节点，该链表中存放的元素就是两个给定链表合并之后的元素
49         ListNode head = new ListNode(-1);
50         ListNode head_temp = head;
51         //定义两个指针分别指向两个给定的链表list1和list2
52         ListNode temp1 = list1;
53         ListNode temp2 = list2;
54         //当两个临时指针都不为空的时候
55         while (temp1 != null && temp2 != null) {
56             //这里使用的是尾插法创建链表
57             if (temp1.val <= temp2.val) {
58                 ListNode temp = temp1.next;
59                 head_temp.next = temp1;
60                 head_temp = head_temp.next;
61                 temp1 = temp;
62             } else {
63                 ListNode temp = temp2.next;
64                 head_temp.next = temp2;
65                 head_temp = head_temp.next;
66                 temp2 = temp;
67             }
68         }
69         //这种情况是当list2已经遍历完了但是list1还没有遍历完，这时候还需要把list1剩余部分全部添加到新链表的后面
70         if (temp1 != null) {
71             head_temp.next = temp1;
72         }
73         //这种情况是当list1已经遍历完了但是list2还没有遍历完，这时候还需要把list2剩余部分全部添加到新链表的后面
74         if (temp2 != null) {
75             head_temp.next = temp2;
76         }
77         //因为创建的头节点只是为了方便操作，所以在最后输出返回值的时候需要去掉
78         return head.next;
79     }
80 }