LeetCode@LinkedList_21_Merge_Two_Sorted_Lists_java linkedlist merge(linkedlist l1, linkedlist l2

Problem Discription

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.

Java Programming

/*
 * 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. 
 * 
 * */
class ListNode
{
	int val;
	ListNode next;
 
	ListNode(int x)
	{
		val = x;
	}
}
 
public class Ans21_Merge_Two_Sorted_Lists
{
	public ListNode mergeTwoLists(ListNode l1, ListNode l2)
	{
		if (l1 == null && l2 == null)
		{
			return null;
		}
 
		ListNode lm = new ListNode(0);
		ListNode head = lm;
		while (l1 != null && l2 != null)
		{
			if (l1.val <= l2.val)
			{
				lm.next = l1;
				l1 = l1.next;
			}
			else
			{
				lm.next = l2;
				l2 = l2.next;
			}
			lm = lm.next;
		}
 
		if (l1 == null)
		{
			lm.next = l2;
		}
		else if (l2 == null)
		{
			lm.next = l1;
		}
 
		return head.next;
 
	}
 
}