1. # 将两个升序链表合并为一个新的 升序 链表并返回。新链表是通过拼接给定的两个链表的所有节点组成的。 
    2. # 
    3. #  
    4. # 
    5. #  示例 1： 
    6. # 
    7. #  
    8. # 输入：l1 = [1,2,4], l2 = [1,3,4]
    9. # 输出：[1,1,2,3,4,4]
    10. #  
    11. # 
    12. #  示例 2： 
    13. # 
    14. #  
    15. # 输入：l1 = [], l2 = []
    16. # 输出：[]
    17. #  
    18. # 
    19. #  示例 3： 
    20. # 
    21. #  
    22. # 输入：l1 = [], l2 = [0]
    23. # 输出：[0]
    24. #  
    25. # 
    26. #  
    27. # 
    28. #  提示： 
    29. # 
    30. #  
    31. #  两个链表的节点数目范围是 [0, 50] 
    32. #  -100 <= Node.val <= 100 
    33. #  l1 和 l2 均按 非递减顺序 排列 
    34. #  
    35. #  Related Topics 递归 链表 
    36. #  👍 1469 👎 0
    39. # leetcode submit region begin(Prohibit modification and deletion)
    40. # Definition for singly-linked list.
    41. # class ListNode(object):
    42. #     def __init__(self, val=0, next=None):
    43. #         self.val = val
    44. #         self.next = next
    47. class Solution(object):
    48.     def mergeTwoLists(self, l1, l2):
    49.         """
    50.         :type l1: ListNode
    51.         :type l2: ListNode
    52.         :rtype: ListNode
    53.         """
    54.         dummyHead = ListNode(0)
    55.         point = dummyHead
    56.         while l1 or l2:
    57.             if (l1 and l2 and l1.val <= l2.val) or (not l2):
    58.                 point.next = ListNode(l1.val)
    59.                 l1 = l1.next
    60.             else:
    61.                 point.next = ListNode(l2.val)
    62.                 l2 = l2.next
    63.             point = point.next
    64.         return dummyHead.next
    65. # leetcode submit region end(Prohibit modification and deletion)