21 Merge Two Sorted Lists Leetcode Problem Javascript Solution

Merge Two Sorted Lists | Leetcode Problem | Javascript Solution

Easy

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->4

class ListNode {
  constructor(val, next=null) {
    this.val = val;
    this.next = next;
  }
}

const c = new ListNode(4);
const b = new ListNode(2, c);
const a = new ListNode(1, b);
const z = new ListNode(3);
const y = new ListNode(2, z);
const x = new ListNode(1, y);

var mergeTwoLists = function(l1, l2) {

  let p1 = l1;
  let p2 = l2;
  let l3, p3;
  if(l1) {
      if (l2){
          if(p1.val < p2.val) {
            l3 = new ListNode(p1.val);
            p1 = p1.next;
          } else {
            l3 = new ListNode(p2.val);
            p2 = p2.next;
          }
      } else {
          return l1;
      }
  } else if(l2) {
      return l2;
  } else {
      return "";
  }
  p3 = l3;

  while(p1 && p2) {
    if(p1.val < p2.val) {
      p3.next = new ListNode(p1.val);
      p1 = p1.next;
    } else {
      p3.next = new ListNode(p2.val);
      p2 = p2.next;
    }
    p3 = p3.next;
  }
  if (p1) {
    p3.next = p1;
  } else {
    p3.next = p2;
  }
  return l3;
}

console.log(mergeTwoLists(a, x));

Run the code here: https://repl.it/@VinitKhandelwal/21-Merge-2-Sorted-Lists-Leetcode-Problem-Javascript-Solution