diff --git a/problems/0206.翻转链表.md b/problems/0206.翻转链表.md index d558e783..0425e182 100644 --- a/problems/0206.翻转链表.md +++ b/problems/0206.翻转链表.md @@ -193,9 +193,9 @@ class Solution { } ``` -Python迭代法: +Python ```python -#双指针 +(版本一)双指针法 # Definition for singly-linked list. # class ListNode: # def __init__(self, val=0, next=None): @@ -205,7 +205,7 @@ class Solution: def reverseList(self, head: ListNode) -> ListNode: cur = head pre = None - while(cur!=None): + while cur: temp = cur.next # 保存一下 cur的下一个节点,因为接下来要改变cur->next cur.next = pre #反转 #更新pre、cur指针 @@ -217,6 +217,7 @@ class Solution: Python递归法: ```python +(版本二)递归法 # Definition for singly-linked list. # class ListNode: # def __init__(self, val=0, next=None): @@ -224,36 +225,17 @@ Python递归法: # self.next = next class Solution: def reverseList(self, head: ListNode) -> ListNode: - - def reverse(pre,cur): - if not cur: - return pre - - tmp = cur.next - cur.next = pre - - return reverse(cur,tmp) - - return reverse(None,head) + return self.reverse(head, None) + def reverse(self, cur: ListNode, pre: ListNode) -> ListNode: + if cur == None: + return pre + temp = cur.next + cur.next = pre + return self.reverse(temp, cur) ``` -Python递归法从后向前: -```python -# 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]: - if not head or not head.next: return head - p = self.reverseList(head.next) - head.next.next = head - head.next = None - return p -``` Go: