题解 | #链表内指定区间反转#

import java.util.*;

public class Solution {

ListNode preNode = null;

public ListNode reverseBetween (ListNode head, int m, int n) {
    // write code here
    return partReverse(head,m,n);
}

public ListNode partReverse (ListNode node,int m,int n){
        if(m==1){
            return ReverseN(node,n);
        }
        node.next = partReverse(node.next,--m,--n);
        return node;
    }
    
public ListNode ReverseN(ListNode node,int n){
    if(n == 1){
        preNode = node.next;
        return node;
    }
    ListNode newNode = ReverseN(node.next,--n);
    node.next.next = node;
    node.next = preNode;
    return newNode;
 }
}