Leetcode---21. Merge Two Sorted Lists

Description:

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.

Solution:

https://leetcode.com/submissions/detail/109508058/

/**
 * Definition for singly-linked list.
 * function ListNode(val) {
 *     this.val = val;
 *     this.next = null;
 * }
 */
/**
 * @param {ListNode} l1
 * @param {ListNode} l2
 * @return {ListNode}
 */
var mergeTwoLists = function(l1, l2) {
    if(l1 == null) return l2;
    if(l2 == null) return l1;
    if(l1.val >l2.val) {
        l2.next =mergeTwoLists(l1,l2.next);
        return l2;
    }else {
        l1.next = mergeTwoLists(l1.next, l2);
        return l1;
    }
};