题解 | #链表内指定区间反转#

# class ListNode:

# from numpy import right_shift
#     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
        # 新建一个链表 连接上主链表
        new_list = ListNode(-1)
        new_list.next = head
        # 获取主链表中需要反转的内容 生产新链表
        # 剔除左边
        left_list = new_list
        for i in range(m - 1):
            left_list = left_list.next
        # return left_list
        # 剔除右边
        right_list = left_list
        for i in range(n - m + 1):
            right_list = right_list.next
        left_node = left_list.next
        succ = right_list.next
        left_list.next = None
        right_list.next = None
        # 反转链表
        prev = None
        current_list = left_node
        while current_list:
            current_node = current_list.next
            current_list.next = prev
            prev = current_list
            current_list = current_node
        # 拼接链表
        left_list.next = prev
        left_node.next = succ
        return new_list.next