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.

思路： 新生成的链表指向第一条链表

java代码：

1. public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
2. if(l1==null) return l2;
3. if(l2==null) return l1;
4. ListNode dummy = new ListNode(-1);
5. ListNode p=dummy;
6. p.next = l1;
7. while(l1!=null&&l2!=null) {
8. if(l2.val < l1.val) {
9. p.next = l2;
10. l2 = l2.next;
11. } else {
12. l1 = l1.next;
13. }
14. p = p.next;
15. p.next = l1;
16. }
17. if(l2!=null) {
18. p.next = l2;
19. }
20. return dummy.next;
21. }