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Update linked_list.js #773

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313 changes: 126 additions & 187 deletions DSA Javascript/linked_list.js
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Original file line number Diff line number Diff line change
@@ -1,230 +1,169 @@
class Node {
// constructor
constructor(element) {
this.element = element;
this.next = null
this.next = null;
}
}
// linkedlist class

class LinkedList {
constructor() {
this.head = null;
this.tail = null;
this.size = 0;
}

// adds an element at the end
// of list

// Adds an element at the end of the list
add(element) {
// creates a new node
var node = new Node(element);

// to store current node
var current;

// if list is Empty add the
// element and make it head
if (this.head == null)
const node = new Node(element);
if (!this.head) {
this.head = node;
else {
current = this.head;

// iterate to the end of the
// list
while (current.next) {
current = current.next;
}

// add node
current.next = node;
this.tail = node;
} else {
this.tail.next = node;
this.tail = node;
}
this.size++;
}

// insert element at the position index
// of the list

// Inserts an element at a given index
insertAt(element, index) {
if (index < 0 || index > this.size)
return console.log("Please enter a valid index.");
else {
// creates a new node
var node = new Node(element);
var curr, prev;

curr = this.head;

// add the element to the
// first index
if (index == 0) {
node.next = this.head;
this.head = node;
} else {
curr = this.head;
var it = 0;

// iterate over the list to find
// the position to insert
while (it < index) {
it++;
prev = curr;
curr = curr.next;
}

// adding an element
node.next = curr;
prev.next = node;
}
this.size++;
if (index < 0 || index > this.size) {
console.log("Invalid index");
return;
}

const node = new Node(element);

if (index === 0) {
node.next = this.head;
this.head = node;
if (this.size === 0) this.tail = node;
} else {
let prev = this.getNodeAt(index - 1);
node.next = prev.next;
prev.next = node;
if (!node.next) this.tail = node;
}
this.size++;
}

// removes an element from the
// specified location

// Removes an element from a specified index
removeFrom(index) {
if (index < 0 || index >= this.size)
return console.log("Please Enter a valid index");
else {
var curr, prev, it = 0;
curr = this.head;
prev = curr;

// deleting first element
if (index === 0) {
this.head = curr.next;
} else {
// iterate over the list to the
// position to removce an element
while (it < index) {
it++;
prev = curr;
curr = curr.next;
}

// remove the element
prev.next = curr.next;
}
this.size--;

// return the remove element
return curr.element;
if (index < 0 || index >= this.size) {
console.log("Invalid index");
return null;
}

let removedElement;

if (index === 0) {
removedElement = this.head.element;
this.head = this.head.next;
if (!this.head) this.tail = null;
} else {
let prev = this.getNodeAt(index - 1);
removedElement = prev.next.element;
prev.next = prev.next.next;
if (!prev.next) this.tail = prev;
}

this.size--;
return removedElement;
}

// removes a given element from the
// list

// Removes a given element from the list
removeElement(element) {
var current = this.head;
var prev = null;

// iterate over the list
while (current != null) {
// comparing element with current
// element if found then remove the
// and return true
if (current.element === element) {
if (prev == null) {
this.head = current.next;
} else {
prev.next = current.next;
}
this.size--;
return current.element;
}
prev = current;
current = current.next;
if (!this.head) return -1;

if (this.head.element === element) {
this.head = this.head.next;
if (!this.head) this.tail = null;
this.size--;
return element;
}
return -1;

let prev = this.head;
while (prev.next && prev.next.element !== element) {
prev = prev.next;
}

if (!prev.next) return -1;

const removedElement = prev.next.element;
prev.next = prev.next.next;
if (!prev.next) this.tail = prev;
this.size--;

return removedElement;
}


// finds the index of element

// Finds the index of an element
indexOf(element) {
var count = 0;
var current = this.head;

// iterate over the list
while (current != null) {
// compare each element of the list
// with given element
if (current.element === element)
return count;
count++;
let current = this.head, index = 0;
while (current) {
if (current.element === element) return index;
current = current.next;
index++;
}

// not found
return -1;
}
// checks the list for empty

// Checks if the list is empty
isEmpty() {
return this.size == 0;
return this.size === 0;
}
// gives the size of the list

// Returns the size of the list
size_of_list() {
console.log(this.size);
return this.size;
}


// prints the list items

// Prints the list
printList() {
var curr = this.head;
var str = "";
while (curr) {
str += curr.element + " ";
curr = curr.next;
let result = [];
let current = this.head;
while (current) {
result.push(current.element);
current = current.next;
}
console.log(result.join(" "));
}

// Helper method to get the node at a specific index
getNodeAt(index) {
let current = this.head;
for (let i = 0; i < index; i++) {
current = current.next;
}
console.log(str);
return current;
}

}

// creating an object for the
// Linkedlist class
var ll = new LinkedList();

// testing isEmpty on an empty list
// returns true
console.log(ll.isEmpty());

// adding element to the list

// Testing the optimized LinkedList
let ll = new LinkedList();

console.log(ll.isEmpty()); // true

ll.add(10);

// prints 10
ll.printList();

// returns 1
console.log(ll.size_of_list());

// adding more elements to the list
ll.printList(); // 10

console.log(ll.size_of_list()); // 1

ll.add(20);
ll.add(30);
ll.add(40);
ll.add(50);

// returns 10 20 30 40 50
ll.printList();

// prints 50 from the list
console.log("is element removed ?" + ll.removeElement(50));

// prints 10 20 30 40
ll.printList();

// returns 3
console.log("Index of 40 " + ll.indexOf(40));

// insert 60 at second position
// ll contains 10 20 60 30 40
ll.printList(); // 10 20 30 40 50

console.log("Is element removed? " + ll.removeElement(50)); // 50
ll.printList(); // 10 20 30 40

console.log("Index of 40: " + ll.indexOf(40)); // 3

ll.insertAt(60, 2);

ll.printList();

// returns false
console.log("is List Empty ? " + ll.isEmpty());

// remove 3rd element from the list
console.log(ll.removeFrom(3));

// prints 10 20 60 40
ll.printList();
ll.printList(); // 10 20 60 30 40

console.log("Is list empty? " + ll.isEmpty()); // false

console.log(ll.removeFrom(3)); // 30
ll.printList(); // 10 20 60 40