React-Native-Cache-PartII
建立雙向鍊表的 Class
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| class Node {
constructor(data) {
this.data = data;
this.prev = null;
this.next = null;
}
}
class DoubleLinklist {
constructor() {
this.head = null;
this.tail = null;
this.length = 0;
}
append(data){
const newNode = new Node(data);
console.log('this.length', this.length);
console.log('this', this);
if (this.length === 0) {
this.tail = newNode;
this.head = newNode;
} else {
newNode.prev = this.tail;
this.tail.next = newNode;
this.tail = newNode;
}
this.length += 1;
};
}
let list = new DoubleLinklist();
list.append('aaa');
list.append('bbb');
list.append('ccc');
console.log(list);
|
情境一
情境二
結果
完整範例
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| class Node {
constructor(data) {
this.data = data;
this.prev = null;
this.next = null;
}
}
class DoubleLinklist {
constructor() {
this.head = null;
this.tail = null;
this.length = 0;
}
toString() {
return this.backwardString();
}
forwardString() {
let current =this.tail;
let resultString = "";
while (current) {
resultString += current.data + "--";
current = current.prev;
}
return resultString;
}
backwardString() {
let current = this.head;
let resultString = "";
while (current) {
resultString += current.data + "--";
current = current.next;
}
return resultString;
}
indexOf(data){
let current = this.head;
let index = 0;
while(current){
if (current.data == data) {
return index;
}
current = current.next;
index += 1;
}
return -1;
}
removeAt(position){
if (position < 0 || position >= this.length) {
return null;
}
let 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 - 1){
current = this.tail;
this.tail.prev.next = null;
this.tail = this.tail.prev;
}else{
let index = 0;
while(index++ < position){
current = current.next;
}
current.next.prev = current.prev;
current.prev.next = current.next;
}
}
this.length -= 1;
return current.data;
}
remove(data) {
const index = this.indexOf(data);
return this.removeAt(index);
}
isEmpty(){
return this.length == 0;
}
size() {
return this.length;
}
getHead(){
return this.head.data;
}
getTail (){
return this.tail.data;
}
insert(position, data) {
if (position < 0 || position > this.length) return false
let newNode = new Node(data);
if (this.length == 0) {
this.head = newNode;
this.tail = newNode;
}else {
if (position == 0) {
this.head.prev = newNode;
newNode.next = this.head;
this.head = newNode;
} else if(position == this.length){
this.tail.next = newNode;
newNode.prev = this.tail;
this.tail = newNode;
}else{
let current = this.head;
let index = 0;
while(index++ < position){
current = current.next;
}
newNode.next = current;
newNode.prev = current.prev;
current.prev.next = newNode;
current.prev = newNode;
}
}
this.length += 1;
return true;
}
append(data){
const newNode = new Node(data);
console.log('this.length', this.length);
console.log('this', this);
if (this.length === 0) {
this.tail = newNode;
this.head = newNode;
} else {
newNode.prev = this.tail;
this.tail.next = newNode;
this.tail = newNode;
}
this.length += 1;
};
}
let list = new DoubleLinklist();
list.append('a')
list.append('b')
list.append('c')
list.append('d')
console.log(list.remove('a'));
console.log(list);
console.log(list.isEmpty());
console.log(list.size());
console.log(list.getHead());
console.log(list.getTail());
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