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.
Example:
Input: 1->2->4, 1->3->4
Output: 1->1->2->3->4->4Solution:
/**
* 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;
const head = l1.val < l2.val ? l1 : l2;
if (l1.val < l2.val) {
head.next = mergeTwoLists(l1.next, l2);
} else {
head.next = mergeTwoLists(l1, l2.next);
}
return head;
};