题解 | 链表中的节点每k个一组翻转

import java.util.*;

/*
 * public class ListNode {
 *   int val;
 *   ListNode next = null;
 *   public ListNode(int val) {
 *     this.val = val;
 *   }
 * }
 */

public 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 k int整型 
     * @return ListNode类
     */
    public ListNode reverseKGroup (ListNode head, int k) {
        // write code here
        ListNode node = head;
        for(int i = 0 ; i < k ; i++)
        {
            if(node == null)
            {
            return head;
            }
            node = node.next;
        }
        ListNode prev = null;
        ListNode cur = head;
        for(int i = 0 ; i < k ; i ++)
        {
            ListNode nextTemp = cur.next;
            cur.next = prev;
            prev = cur;
            cur = nextTemp;
        }
        head.next = reverseKGroup(cur,k);
        return prev;
    }
}