题解 | #链表内指定区间反转#

from os import removexattr

# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None
#
# 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
#
#
# @param head ListNode类
# @param m int整型
# @param n int整型
# @return ListNode类
#
class Solution:
    def reverseBetween(self, head: ListNode, m: int, n: int) -> ListNode:
        # write code here
        prehead = ListNode(-1)
        prehead.next = head

        count = 1
        pre = prehead
        curr = head

        while count < m:
            pre = curr
            curr = curr.next
            count += 1

        # 已经找到m，开始反转,count=m

        while count < n:
            temp = curr.next
            curr.next = temp.next
            temp.next = pre.next
            pre.next = temp
            # 更新pre，curr
            # pre = curr
            # curr = temp
            count += 1
            # print(count)

        return prehead.next