Merge two sorted linked lists and return it as a new sorted list. The new list should be made by splicing together the nodes of the first two lists.

MergeTwoLists.cs

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     public int val;
 *     public ListNode next;
 *     public ListNode(int val=0, ListNode next=null) {
 *         this.val = val;
 *         this.next = next;
 *     }
 * }
 */
public class Solution {
    public ListNode MergeTwoLists(ListNode l1, ListNode l2) {
     
        ListNode newList = new ListNode();
        ListNode dummyHead = newList;
        ListNode l1temp = l1;
        ListNode l2temp = l2;
        
        while(l1temp!=null && l2temp!=null){
            
            if(l1temp.val<l2temp.val){
                dummyHead.next = new ListNode(l1temp.val);
                l1temp = l1temp.next;
            }
            else{
                dummyHead.next = new ListNode(l2temp.val);
                l2temp = l2temp.next;
            }        
            dummyHead = dummyHead.next;
        }
        
        if(l1temp == null){
            while(l2temp!=null){
                dummyHead.next = new ListNode(l2temp.val);
                l2temp = l2temp.next;
                dummyHead = dummyHead.next;
            }
            
        }
        
        if(l2temp == null){
            while(l1temp!=null){
                dummyHead.next = new ListNode(l1temp.val);
                l1temp = l1temp.next;
                dummyHead = dummyHead.next;
            }
        }
        
        return newList.next;
    }
}