21. Merge Two Sorted Lists leetcode Python 2016 new Season

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 = Noneclass Solution(object):    def mergeTwoLists(self, l1, l2):        """        :type l1: ListNode        :type l2: ListNode        :rtype: ListNode        """        dummyHead = head = ListNode(None)        while l1 and l2:            if l1.val < l2.val:                head.next = l1                l1 = l1.next                head = head.next            else:                head.next = l2                l2 = l2.next                head = head.next        if l1:            head.next = l1        if l2:            head.next = l2        return dummyHead.next