golang go语言 实现链表

package main

import (
	"errors"
	"fmt"
	"strconv"
)

type List struct {
	Length int
	Head  *Node
}

type Node struct {
	NextNode *Node
	Value int
}

func (list *List) IsEmpty() bool {
	return list.Length == 0
}

func (list *List) Append(value int) {
	list.Length += 1
	if list.Head == nil {
		list.Head = &Node{Value: value}
		return
	}
	lastNode := list.Head
	for lastNode.NextNode != nil {
		lastNode = lastNode.NextNode
	}
	lastNode.NextNode = &Node{Value: value}
}

func (list *List) Delete(index int) error {
	if index + 1 > list.Length {
		return errors.New("index out of range")
	}
	list.Length -= 1
	if index == 0{
		list.Head = list.Head.NextNode
		return nil
	}
	indexNode := list.Head
	for i := index; i > 1; i-- {
		indexNode = indexNode.NextNode
	}
	if indexNode.NextNode != nil {
		indexNode.NextNode = indexNode.NextNode.NextNode
	} else {
		indexNode.NextNode = nil
	}
	return nil
}

func (list *List) String() string {
	var ret string
	node := list.Head
	for node.NextNode != nil {
		ret += strconv.Itoa(node.Value) + ","
		node = node.NextNode
	}
	ret += strconv.Itoa(node.Value)
	return ret
}

func (list *List) Insert(index, value int) error {
	if index + 1 > list.Length {
		return errors.New("index out of range")
	}
	list.Length++
	if index == 0{
		list.Head = &Node{Value:value, NextNode:list.Head}
		return nil
	}
	indexNode := list.Head
	for i := index; i > 1; i-- {
		indexNode = indexNode.NextNode
	}
	tempNode := &Node{Value: value, NextNode: indexNode.NextNode}
	indexNode.NextNode = tempNode
	return nil
}

func main() {
	a := List{}
	for i := 0; i < 10; i++ {
		a.Append(i)
	}
	fmt.Println(a.String())
	if err := a.Insert(9, 99); err != nil{
		fmt.Println(err)
	}
	fmt.Println(a.String())
}