LeetCode: Merge Two Sorted Lists 解题报告

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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！

 /**

  * Definition for singly-linked list.

  * public class ListNode {

  *     int val;

  *     ListNode next;

  *     ListNode(int x) {

  *         val = x;

  *         next = null;

  *     }

  * }

  */

 public class Solution {

     public ListNode mergeTwoLists(ListNode l1, ListNode l2) {

         ListNode dummy = new ListNode();

         ListNode cur = dummy;

         while (l1 != null && l2 != null) {

             if (l1.val < l2.val) {

                 cur.next = l1;

                 l1 = l1.next;

             } else {

                 cur.next = l2;

                 l2 = l2.next;

             }

             cur = cur.next;

         }

         if (l1 != null) {

             cur.next = l1;

         } else {

             cur.next = l2;

         }

         return dummy.next;

     }

 }