题解 | #链表内指定区间反转#

#coding:utf-8
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 , m , n ):
        # write code here
        if m == n:
            return head

        flag = ListNode(0)
        flag.next = head
        pre = flag
        cur = head
        i = 1
        while cur:
            nex = cur.next
            if i == m:
                flag1 = pre
                flag2 = cur
            if i > m and i <= n:
                cur.next = pre
            if i == n:
                flag1.next = cur
                flag2.next = nex
            pre = cur
            cur = nex
            i += 1

        return flag.next

头节点需要单独保存一个，用来返回。