21. 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.

归并两个有序链表，此题看完你应该去看看算法中的归并排序是如何实现的

/** * Definition for singly-linked list. * public class ListNode { * int val; * ListNode next; * ListNode(int x) { val = x; } * } */ public class Solution { public ListNode mergeTwoLists(ListNode l1, ListNode l2) { ListNode l3=new ListNode(0); ListNode head=l3; while(l1!=null||l2!=null){ if(l1==null){ l3.next=l2; break; } if(l2==null){ l3.next=l1; break; } if(l1.val<l2.val){ l3.next=l1; l1=l1.next; }else{ l3.next=l2; l2=l2.next ; } l3=l3.next; } return head.next; } }