题目浅析

  • 想查看原题可以点击题目链接。

  • 简单地说，就是要将链表中的一段反转，这一段可以是任意长度任意位置的一段。

思路分享

代码解答（强烈建议自行解答后再看）

  • 参考题解
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# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    def reverseBetween(self, head: Optional[ListNode], left: int, right: int) -> Optional[ListNode]:
        dummy = ListNode(-1, head)
        p0 = dummy
        for _ in range(left-1):
            p0 = p0.next
        
        pre = None
        cur = p0.next
        for _ in range(right-left+1):
            nxt = cur.next
            cur.next = pre
            pre = cur
            cur = nxt 
        
        p0.next.next = cur
        p0.next = pre

        return dummy.next