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！

 /**
  * 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;
     }
 }

GITHUB:

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