题解 | #链表中的节点每k个一组翻转#

package main
import . "nc_tools"
/*
 * type ListNode struct{
 *   Val int
 *   Next *ListNode
 * }
 */

/**
 * 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
*/
func reverseKGroup( head *ListNode ,  k int ) *ListNode {
    tail := head
    for i := 0; i < k; i++ {
        if tail == nil {
            return head 
        }
        tail = tail.Next
    }
    cur := head
    var pre *ListNode
    for i := 0 ;;i++  {
        if cur == tail {
            break
        }
        temp := cur.Next
        cur.Next = pre
        pre = cur
        cur = temp
    }
    head.Next = reverseKGroup(tail, k)
    return pre
}