面试题22. 链表中倒数第k个节点

面试题22. 链表中倒数第k个节点

package main
import "fmt"
type ListNode struct {
    Val  int
    Next *ListNode
}
func getKthFromEnd1(head *ListNode, k int) *ListNode {
    var res []*ListNode
    for head != nil {
        res = append(res, head)
        head = head.Next
    }
    l := len(res)
    if l >= k {
        return res[l-k]
    }
    return nil
}
func getKthFromEnd(head *ListNode, k int) *ListNode {
    var fast = head
    for k > 0 && fast != nil {
        fast = fast.Next
        k--
    }
    var slow = head
    for fast != nil {
        fast = fast.Next
        slow = slow.Next
    }
    return slow
}
func main() {
    one := &ListNode{Val: 1}
    two := &ListNode{Val: 2}
    one.Next = two
    three := &ListNode{Val: 3}
    two.Next = three
    four := &ListNode{Val: 4}
    three.Next = four
    five := &ListNode{Val: 5}
    four.Next = five
    r := getKthFromEnd(one, 2)
    for r != nil {
        fmt.Println(r.Val)
        r = r.Next
    }
}