I have the next implementation of Linked List:
class Node {
constructor(data) {
this.data = data;
this.next = null;
}
}
class LinkedLIst {
constructor() {
this.head = {};
}
add(head) {
if(!this.head.next) {
this.head = new Node(head);
}
this.head.next = new Node(head);
}
}
const list = new LinkedLIst();
list.add(1)
list.add(2)
list.add(3)
console.log(list)I don't understand, why 2 is not added within the list? And how to fix that?
Since this is a linked list, I am assuming you want to insert at the end. To do that, you can create a tail property.
Then, in you add method, you can check if no elements exist, then set the head and tail to the new node. If there is at least 1 element, you can set the tail's next to the new node and finally, make the tail point to the new node.
class Node {
constructor(data) {
this.data = data;
this.next = null;
}
}
class LinkedLIst {
constructor() {
this.head = null;
this.tail = null;
}
add(value) {
const newNode = new Node(value)
if (this.head === null) {
this.head = this.tail = newNode
} else {
this.tail.next = newNode
this.tail = newNode;
}
}
}
const list = new LinkedLIst();
list.add(1)
list.add(2)
list.add(3)
console.log(list)
tail is going to be the second last element after you insert a new element. So, you are connecting the tail's next to the newNode. Once done, you want to update the tail again to point to the last node which is going to be the newNodetail?head tracks the first node of the linked list, and tail tracks the last node of the linked list.if you don't want to use tail just iterate until the end of the linklist
class Node {
constructor(data) {
this.data = data;
this.next = null;
}
}
class LinkedLIst {
constructor() {
this.head = null;
}
add(head) {
if(!this.head) {
this.head = new Node(head);
}else{
let ptr = this.head;
while(ptr.next!==null){
ptr = ptr.next;
}
ptr.next=new Node(head);
}
}
}
const list = new LinkedLIst();
list.add(1)
list.add(2)
list.add(3)
console.log(list)ptr variable, why i can not use this.head instead?