LeetCode 筆記 - 206. Reverse Linked List

Posted on

題目在此 206. Reverse Linked List

給定一個 Linked list，請反轉它

解題思維

這題筆者是多一個 最後一個 node 參數，一個一個指回去，沒什麼特別的技巧

程式碼

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    def reverseList(self, head: Optional[ListNode]) -> Optional[ListNode]:
        
        def walk(last, current) -> Optional[ListNode]:
            if current is None:
                return last
            
            next_temp = current.next
            current.next = last
            
            return walk(current, next_temp)
        return walk(None, head)

相關文章