题解 | #链表内指定区间反转#

using System;
using System.Collections.Generic;

/*
public class ListNode
{
    public int val;
    public ListNode next;

    public ListNode (int x)
    {
        val = x;
    }
}
*/

class Solution {
    /**
     * 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
     */
    public ListNode reverseBetween (ListNode head, int m, int n) {
        // write code here
        if (head == null)
            return null;
        if (m > n)
            return head;
        int nCount = 0;
        ListNode lnRtnL, lnRtn, lnRtnR;
        lnRtnR = lnRtnL = lnRtn = new ListNode(0);
        while (head != null) {
            nCount++;
            if (nCount >= m && nCount <= n) {
                ListNode ln = lnRtnL.next;
                lnRtnL.next = head;
                head = head.next;
                lnRtnL.next.next = ln;
                if (lnRtnR.next != null)
                    lnRtnR = lnRtnR.next;
            } else {
                ListNode ln = lnRtnR.next;
                lnRtnR.next = head;
                head = head.next;
                lnRtnR = lnRtnR.next;
                lnRtnR.next = null;
                lnRtnL = lnRtnR;
            }
        }
        return lnRtn.next;
    }
}