'''
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.
'''

# Definition for singly-linked list.
# class ListNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution(object):
    def mergeTwoLists(self, l1, l2):
        """
        :type l1: ListNode
        :type l2: ListNode
        :rtype: ListNode
        """
        
        result = ListNode(0)
        if not l1 :
            return l2
        if not l2 :
            return l1

        if l1.val < l2.val:
            result = l1
            result.next = self.mergeTwoLists(l1.next,l2)
        else:
            result = l2
            result.next = self.mergeTwoLists(l2.next,l1)

        return result
