141. 环形链表 golang

Me

func hasCycle(head *ListNode) bool {
	if head == nil {
		return false
	}
    firstNode, secondNode := head, head.Next
	for secondNode != nil && secondNode.Next != nil {
		if firstNode == secondNode {
			return true
		}
		firstNode = firstNode.Next
		secondNode = secondNode.Next.Next
	}
	return false
}