在Python中合并两个排序链表

我不是超级链表经验丰富,但正在努力解决更多的问题,以获得曝光。我的代码没有返回所需的输出[1,1,2,3,4,4],而是返回[4]。不过,我认为主要的逻辑是存在的,我希望错过一些小东西。

def mergeTwoLists(self, l1, l2):
        """
        :type l1: ListNode
        :type l2: ListNode
        :rtype: ListNode
        """
        newList = ListNode(0) # used for single, merged list
        while l1 and l2:
            if l1.val <= l2.val: # compare current node's values
                newList.next = l1
                l1 = l1.next
            else:
                newList.next = l2
                l2 = l2.next

        return newList.next # first node is 0, which we don't want