题目:

代码:

func reverseKGroup(head *ListNode, k int) *ListNode {
	cur := head
	for i := 0; i < k; i++ {
		if cur == nil {
			return head
		}
		cur = cur.Next
	}
	newHead := reverse(head, cur)
	head.Next = reverseKGroup(cur, k)
	return newHead
}

func reverse(start, end *ListNode) *ListNode { //翻转
	var pre *ListNode
	cur := start
	for cur != end {
		nex := cur.Next
		cur.Next = pre
		pre = cur
		cur = nex
	}
	return pre
}