leetcode 92翻转链表 递归

题目描述

思路

函数思想

1. 创建reverseN 递归
2. 找到需要递归的点

代码

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    //存放后面未翻转节点
    ListNode *succ = NULL;
    ListNode *reverseN(ListNode *head,int n)
    {
        if(n==1)
        {
            succ = head->next;
            return head;
        }
        //翻转n个节点，直到剩余一个节点
        ListNode*ret = reverseN(head->next,n-1);
        head->next->next = head;
        head->next = succ;
        return ret;
    }
    
    ListNode* reverseBetween(ListNode* head, int m, int n) {
        if(m==1)
            return reverseN(head,n);
        //进行移动 
        head->next = reverseBetween(head->next,m-1,n-1);
        return head;
    }
};

重难点

移动时 head->next = reverseBetween(head->next);