题解 | #链表内指定区间反转#

递归，先实现反转链表的前N个节点，再用递归来反转区间

# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None

#
# 
# @param head ListNode类 
# @param m int整型 
# @param n int整型 
# @return ListNode类
#
class Solution:
    def reverseBetween(self , head , m , n ):
        # write code here
        self.successor = None
        def reverseN(head, n):
            if n == 1:
                self.successor = head.next
                return head
            last = reverseN(head.next, n-1)
            head.next.next = head
            head.next = self.successor
            return last
        if m == 1:
            return reverseN(head, n)
        head.next = self.reverseBetween(head.next, m-1, n-1)
        return head