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leetcode 【 Merge Two Sorted Lists 】 python 实现

题目

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.

 

代码:oj在线测试通过 Runtime: 208 ms

 1 # Definition for singly-linked list. 2 # class ListNode: 3 #     def __init__(self, x): 4 #         self.val = x 5 #         self.next = None 6  7 class Solution: 8     # @param two ListNodes 9     # @return a ListNode10     def mergeTwoLists(self, l1, l2):11         if l1 is None:12             return l213         if l2 is None:14             return l115         16         dummyhead = ListNode(0)17         dummyhead.next = None18         p = dummyhead19         while l1 is not None and l2 is not None:20             if l1.val > l2.val:21                 p.next = l222                 l2 = l2.next23             else:24                 p.next = l125                 l1 = l1.next26             p = p.next27         if l1 is not None:28             p.next = l129         else:30             p.next = l231         return dummyhead.next

 

思路

虚表头dummyhead设定好了就不要动,设定一个p=hummyhead,然后从处理p.next开始;最后返回hummyhead就可以获得正确的结果

两个表的指针一步步移动,并通过比较val的大小决定哪个插入p.next

注意,每次执行完判断,要移动指针p=p.next

leetcode 【 Merge Two Sorted Lists 】 python 实现