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.

Solution

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
public class Solution {
    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
         if (l1 == null)
            return l2;

        if (l2 == null)
            return l1;

        ListNode start, runner1, runner2;
        if (l1.val <= l2.val) {
            start = new ListNode(l1.val);
            runner1 = l1.next;
            runner2 = l2;
        } else {
            start = new ListNode(l2.val);
            runner1 = l1;
            runner2 = l2.next;
        }

        ListNode result = start;
        while (runner1 != null && runner2 != null) {
            if (runner1.val <= runner2.val) {
                start.next = new ListNode(runner1.val);
                runner1 = runner1.next;
            } else {
                start.next = new ListNode(runner2.val);
                runner2 = runner2.next;
            }

            start = start.next;
        }

        if (runner1 == null) {
            while (runner2 != null) {
                start.next = new ListNode(runner2.val);
                start = start.next;
                runner2 = runner2.next;
            }

        } else {
            while (runner1 != null) {

                start.next = new ListNode(runner1.val);
                start = start.next;
                runner1 = runner1.next;
            }

        }


        return result;


    }
}