92. Reverse Linked List II

Reverse a linked list from position m to n. Do it in one-pass.

Note: 1 ≤ m ≤ n ≤ length of list.

Example:

Input: 1->2->3->4->5->NULL, m = 2, n = 4
Output: 1->4->3->2->5->NULL

来源：力扣（LeetCode）
链接：https://leetcode-cn.com/problems/reverse-linked-list-ii
著作权归领扣网络所有。商业转载请联系官方授权，非商业转载请注明出处。

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
class Solution {
    public ListNode reverseBetween(ListNode head, int m, int n) {
        if(head==null || head.next==null) return head;
        ListNode cur = head, pre = null;
        while(m>1){
            pre = cur;
            cur = cur.next;
            --n;
            --m;
        }
        ListNode con = pre, tail = cur;
        while(n>0){
            ListNode temp = cur.next;
            cur.next = pre;
            pre = cur;
            cur = temp;
            --n;
        }
        if(con!=null){
            con.next = pre;
        }else{
            head = pre;
        }
        tail.next = cur;
        return head;
    }
}

来源：CSDN

作者：csdnzhaocsdn

链接：https://blog.csdn.net/qq_39360744/article/details/104180921