1.链表的概念
列表存储的是有序元素集合，不同于数组，链表的中的元素在内存中并不是连续放置的。每个元素是由一个存储元素本身的节点和指向下一个元素的引用(指针或链接)组成。
通过的这个概念的我们可以分析出
某一个节点大概是:
node:{
value:xxx,
next:node
}
除此之外还有length保存着链表的长度,head表示第一个元素在哪里
所以添加元素
2.1添加元素
function LinkedList(){
let Node = function(element){
this.element = element
this.next = null
}
let length = 0
let head = null
// 向列表尾部添加一个新的项
this.append = function(element){
let node = new Node(element), current
if(head === null) {//列表中第一个节点
head = node
}else{
current = head
// 循环列表直到找到最后一项
while(current.next){
current = current.next
}
current.next = node
}
length++
}
this.print = function(){
console.log(head)
}
}
image.png
2.2移除某一个位置
在数组中删除某一项元素是:把第n项的值删除，第n+1项以及n+1项之后的项全部向前移动一位
在链表中删除某一项元素是:把第n-1项的next指向n+1，则自动把第n项删除了
代码实现:
this.remove=function(position){
if(position>=0&&position<length){
let current = head
let prev
if(position===0){
head = current.next
}else{
let index = 0
while(index<position){
prev = current //现任变前任
current = current.next //后任变现任
index++
}
prev.next = current.next // 断掉current
length--
return current
}
}else{
return null
}
}
2.3向指定位置插入新项
与2.2类似，首先需要判断这个位置是不是越界的，index不能在length之外，和0之前，然后通过循环找到position。
this.insert=function(position,element){
if(position<=length&&position>=0){
let current,prev,index = 0
let node = new Node(element)
if(position === 0){ // 位置为head则只需要改变head的值，和指针
current = head
head = node
head.next = current
}else{
current = head
while(index<position){
prev = current
current = current.next
index++
}
prev.next = node
node.next = current
length++
return node
}
}else{
return null
}
}
最后:所有方法的实现
function LinkedList () {
let Node = function (element) {
this.element = element
this.next = null
}
let length = 0
let head = null
// 向列表尾部添加一个新的项
this.append = function (element) {
let node = new Node(element), current
if (head === null) {//列表中第一个节点
head = node
} else {
current = head
// 循环列表直到找到最后一项
while (current.next) {
current = current.next
}
current.next = node
}
length++
}
// 向列表的特定位置插入一个新的项
this.insert = function (position, element) {
if (position <= length && position >= 0) {
let current, prev, index = 0
let node = new Node(element)
if (position === 0) { // 位置为head则只需要改变head的值，和指针
current = head
head = node
head.next = current
} else {
current = head
while (index < position) {
prev = current
current = current.next
index++
}
prev.next = node
node.next = current
length++
return node
}
} else {
return null
}
}
// 从列表的特定位置移除一项
this.removeAt = function (element) {
let index = 0
let current = head
let prev
while (current) {
prev = current
current = current.next
if (current.element === element) {
prev.next = current.next
return current
}
current = current.next
index++
}
return null
}
// 从列表中移除一项
this.remove = function (position) {
if (position >= 0 && position < length) {
let current = head
let prev
if (position === 0) {
head = current.next
} else {
let index = 0
while (index < position) {
prev = current //现任变前任
current = current.next //后任变现任
index++
}
prev.next = current.next // 断掉current
length--
return current
}
} else {
return null
}
}
// 返回元素在列表中的索引
this.indexOf = function (element) {
let index = 0
let current = head
while (current) {
if(current.element === element){
return index
}
current = current.next
index++
}
return null
}
// 如果链表不存在任何元素返回true
this.isEmpty = function () {
if (head) {
return false
}
return true
}
// 返回列表包含的元素个数
this.size = function () {
return length
}
//
this.getHead = function () {
return head
}
this.toString = function () {
return this.toString()
}
this.print = function () {
console.log(head)
}
}
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