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 }

 

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