剑指offer-22-链表中倒数第k个节点-golang

题目：输入一个链表，输出该链表中倒数第k个节点。

type Node struct {
	val  int
	next *Node
}

func findKthTail(head *Node, k int) int {
	if head == nil || k < 1 {
		return -1
	}
	p := head
	count := 0
	for p != nil {
		count++
		p = p.next
	}
	if count < k {
		return -1
	}
	front, tail := head, head
	for i := 0; i < k; i++ {
		front = front.next
	}
	for front != nil {
		front = front.next
		tail = tail.next
	}
	return tail.val
}