21. Merge Two Sorted Lists(合并2个有序链表)

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

需要排序！！！

[2,4]
[1]

输出1 2 4

而不是2 4 1 

 递归版！！

class Solution {
    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
        if(l1==null) return l2;
        if(l2==null) return l1;
        if(l1.val<l2.val) {
            l1.next = mergeTwoLists(l1.next,l2);
            return l1;
        }
        else {
            l2.next = mergeTwoLists(l2.next,l1);
            return l2;
        }
       
    }
    
}