LeetCode: Merge Two Sorted Lists 解题报告

Merge Two Sorted Lists

Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists.

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SOLUTION 1:

使用dummynode记录头节点的前一个，轻松完成，2分钟就AC啦！

 1 /**
 2  * Definition for singly-linked list.
 3  * public class ListNode {
 4  *     int val;
 5  *     ListNode next;
 6  *     ListNode(int x) {
 7  *         val = x;
 8  *         next = null;
 9  *     }
10  * }
11  */
12 public class Solution {
13     public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
14         ListNode dummy = new ListNode(0);
15         ListNode cur = dummy;
16
17         while (l1 != null && l2 != null) {
18             if (l1.val < l2.val) {
19                 cur.next = l1;
20                 l1 = l1.next;
21             } else {
22                 cur.next = l2;
23                 l2 = l2.next;
24             }
25             cur = cur.next;
26         }
27
28         if (l1 != null) {
29             cur.next = l1;
30         } else {
31             cur.next = l2;
32         }
33
34         return dummy.next;
35     }
36 }

GITHUB:

https://github.com/yuzhangcmu/LeetCode_algorithm/blob/master/list/MergeTwoLists_1206.java