1.双向链表
数据结构中常见的操作如下：
// 1.append(element)
// 2.inset(position,element)
// 3.get(position)
// 4.indexOf(element)
// 5.update(position)
// 6.removeAt(position)
// 7.remove(element)
// 8.isEmpty()
// 9.size()
// 10.toString()
// 11.forwardString()
// 12.backwordString()
① 首先应该建立节点
class Node{
constructor(data){
this.data = data;
this.next = null;
this.prev = null;
}
}
② 然后建立链表函数
class doubleLinkList {
constructor() {
this.head = null;
this.tail = null;
this.length = 0;
// 插入各种具体的方法...........................................
}
③ 插入的12个方法如下：
1.append(element) （尾插法）
append(data){
var newNode = new Node(data);
// 判断是否是第一个节点
if (this.length===0){
this.head = newNode;
this.tail = newNode;
}else {
var current = this.head;
// 寻找最后的节点
while (current.next){
current = current.next
}
current.next = newNode;
newNode.prev = current;
this.tail = newNode;
}
// 最后不要忘记长度加一
this.length += 1;
}
2.toString 将链表转化成字符串方法
3.forwardString():返回正向遍历的节点字符串形式
4.backwordString():返回反向遍历的节点字符串形式
// 2.toString 将链表转化成字符串方法
toString(){
return this.backwordString()
}
// 3.forwardString():返回正向遍历的节点字符串形式
forwardString(){
// 从后往前遍历
var current = this.tail;
var resultString = "";
while (current){
resultString += current.data + "";
current = current.prev;
}
return resultString;
}
// 4.backwordString():返回反向遍历的节点字符串形式
backwordString(){
// 1.定义遍历
var current = this.head;
var resultString = "";
// 2.依次向后遍历，获得每一个点
while (current){
resultString += current.data + "";
current = current.next;
}
return resultString;
}
5.insert任意位置插入
分为三种情况：
1.开头插入
2.尾插入
3.中间插入
insert(data,position){
if (position <0 || position > this.length)return false
var newNode = new Node(data)
// 1.原来的列表是否为空
if (this.length == 0){
this.head = newNode;
this.tail = newNode;
}else {
// 2.当在第一个位置
if (position === 0){
this.head.prev = newNode;
newNode.next = this.head;
this.head = newNode;
// 3. 当在最后的位置
}else if (position == this.length){
newNode.prev = this.tail;
this.tail.next = newNode;
this.tail = newNode;
// 4. 当在中间的位置
}else {
var current = this.head;
var index = 0;
while (index++ < position){
current = current.next
}
// 5. 修改指针
newNode.next = current;
newNode.prev = current.prev;
current.prev.next = newNode;
current.prev = newNode;
}
}
this.length += 1;
return true;
}
6. get 方法
get(position){
if (position < 0 ||position >= this.length)return null
if (this.length / 2 > position){
var current = this.head;
var index = 0;
while (index++ < position){
current = current.next;
}
return current.data;
}else {
var current = this.tail;
var index = this.length - 1;
while (index-- > position){
current = current.prev;
}
return current.data;
}
}
7.indexOf() 正反方向一起查，加快速度
indexOf(data){
var current1 = this.head;
var current2 = this.tail;
var index = 0;
var index2 = this.length;
while (current1 && current2){
if (current1.data == data){
return index
}
if (current2.data == data){
return index2
}
current1 = current1.next;
current2 = current2.prev;
index += 1;
index2 -= 1;
}
return false;
}
8.update方法 , 也可以分情况前后查找
update(newdata,position){
if (position < 0 || position >= this.length){return false}
var current = this.head
var index = 0
while (index++ < position){
current = current.next
}
current.data = newdata;
return true;
}
9.removeAt方法
removeAt(position){
// 1.越界判断
if (position < 0 || position > this.length) return false
var current = this.head;
if (this.length == 1){
this.head = null;
this.tail = null;
}else {
if (position == 0){
this.head.next.prev = null;
this.head = this.head.next;
}else if (position == this.length){
this.tail.prev.next = null;
this.tail = this.tail.prev;
}else {
var index = 0;
while (index++ < position){
current = current.next;
}
current.prev.next = current.next;
current.prev.next.prev = current.prev;
}
}
this.length -= 1;
return current.data;
}
10.remove方法
remove(data){
var index = this.indexOf(data);
return this.removeAt(index);
}
12.isEmpty方法
isEmpty(){
return this.length == 0
}
13.size方法
size(){
return this.length
}
打印代码 - 放在链表函数中
// 打印出链表
printList(){
const nodes = []
let current = this.head;
while (current){
nodes.push(current.data);
current = current.next;
}
return nodes.join('-->')
}
④ 测试代码
// 测试代码
// 测试代码
var list = new doubleLinkList();
// 1.测试加入
list.append('aaa');
list.append('bbb');
list.append('ccc');
list.append('ddd');
list.append('eee');
list.append('fff');
list.insert('ggg',6);
console.log("插入'ggg'后 打印链表 ",list.printList());
// 3.测试正反方向分别打印转换的字符串
console.log("正序",list.backwordString());
console.log("正序",list.forwardString());
// 4.获得指定位置的元素
console.log("获得位置是 4 的元素 ",list.get(4));
console.log(" ccc 的位置是 ",list.indexOf('ccc'));
list.update('jojo',2)
console.log("更新位置为 2 的元素 ",list.printList());
list.removeAt(2)
console.log("删除位置为 2 的元素 ",list.printList());
list.remove('ggg');
console.log("移除'ggg' ",list.printList());
console.log("判断是否为空",list.isEmpty());
console.log("判断大小",list.size());
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