// Javascript program to find next right of a given key

// A binary tree node
class Node
{
	constructor(item)
	{
		this.data = item;
		this.left = this.right = null;
	}
}

let root;

// Method to find next right of given key k,
// it returns NULL if k is not present in
// tree or k is the rightmost node of its level
function nextRight(first, k)
{
	
	// Base Case
	if (first == null)
		return null;

	// Create an empty queue for level
	// order traversal. A queue to
	// store node addresses
	let qn = [];
	
	// Another queue to store node levels
	let ql = [];
	
	// Initialize level as 0
	let level = 0;

	// Enqueue Root and its level
	qn.push(first);
	ql.push(level);

	// A standard BFS loop
	while (qn.length != 0)
	{
		
		// dequeue an node from qn and its level from ql
		let node = qn[0];
		level = ql[0];
		qn.shift();
		ql.shift();

		// If the dequeued node has the given key k
		if (node.data == k)
		{
			
			// If there are no more items in queue
			// or given node is the rightmost node
			// of its level, then return NULL
			if (ql.length == 0 || ql[0] != level)
				return null;

			// Otherwise return next node
			// from queue of nodes
			return qn[0];
		}

		// Standard BFS steps: enqueue
		// children of this node
		if (node.left != null)
		{
			qn.push(node.left);
			ql.push(level + 1);
		}
		if (node.right != null)
		{
			qn.push(node.right);
			ql.push(level + 1);
		}
	}

	// We reach here if given key
	// x doesn't exist in tree
	return null;
}

// A utility function to test above functions
function test(node, k)
{
	let nr = nextRight(root, k);
	if (nr != null)
		console.log("Next Right of " + k +
					" is " + nr.data );
	else
		console.log("No next right node found for " +
					k);
}

// Driver code
root = new Node(10);
root.left = new Node(2);
root.right = new Node(6);
root.right.right = new Node(5);
root.left.left = new Node(8);
root.left.right = new Node(4);

test(root, 10);
test(root, 2);
test(root, 6);
test(root, 5);
test(root, 8);
test(root, 4);

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About Javascript

Javascript(JS) is a object-oriented programming language which adhere to ECMA Script Standards. Javascript is required to design the behaviour of the web pages.

Key Features

  • Open-source
  • Just-in-time compiled language
  • Embedded along with HTML and makes web pages alive
  • Originally named as LiveScript.
  • Executable in both browser and server which has Javascript engines like V8(chrome), SpiderMonkey(Firefox) etc.

Syntax help

STDIN Example

var readline = require('readline');
var rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout,
  terminal: false
});

rl.on('line', function(line){
    console.log("Hello, " + line);
});

variable declaration

KeywordDescriptionScope
varVar is used to declare variables(old way of declaring variables)Function or global scope
letlet is also used to declare variables(new way)Global or block Scope
constconst is used to declare const values. Once the value is assigned, it can not be modifiedGlobal or block Scope

Backtick Strings

Interpolation

let greetings = `Hello ${name}`

Multi line Strings

const msg = `
hello
world!
`

Arrays

An array is a collection of items or values.

Syntax:

let arrayName = [value1, value2,..etc];
// or
let arrayName = new Array("value1","value2",..etc);

Example:

let mobiles = ["iPhone", "Samsung", "Pixel"];

// accessing an array
console.log(mobiles[0]);

// changing an array element
mobiles[3] = "Nokia";

Arrow functions

Arrow Functions helps developers to write code in concise way, it’s introduced in ES6.
Arrow functions can be written in multiple ways. Below are couple of ways to use arrow function but it can be written in many other ways as well.

Syntax:

() => expression

Example:

const numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
const squaresOfEvenNumbers = numbers.filter(ele => ele % 2 == 0)
                                    .map(ele => ele ** 2);
console.log(squaresOfEvenNumbers);

De-structuring

Arrays

let [firstName, lastName] = ['Foo', 'Bar']

Objects

let {firstName, lastName} = {
  firstName: 'Foo',
  lastName: 'Bar'
}

rest(...) operator

 const {
    title,
    firstName,
    lastName,
    ...rest
  } = record;

Spread(...) operator

//Object spread
const post = {
  ...options,
  type: "new"
}
//array spread
const users = [
  ...adminUsers,
  ...normalUsers
]

Functions

function greetings({ name = 'Foo' } = {}) { //Defaulting name to Foo
  console.log(`Hello ${name}!`);
}
 
greet() // Hello Foo
greet({ name: 'Bar' }) // Hi Bar

Loops

1. If:

IF is used to execute a block of code based on a condition.

Syntax

if(condition){
    // code
}

2. If-Else:

Else part is used to execute the block of code when the condition fails.

Syntax

if(condition){
    // code
} else {
    // code
}

3. Switch:

Switch is used to replace nested If-Else statements.

Syntax

switch(condition){
    case 'value1' :
        //code
        [break;]
    case 'value2' :
        //code
        [break;]
    .......
    default :
        //code
        [break;]
}

4. For

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
//code  
}

5. While

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while (condition) {  
  // code 
}

6. Do-While

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {  
  // code 
} while (condition);

Classes

ES6 introduced classes along with OOPS concepts in JS. Class is similar to a function which you can think like kind of template which will get called when ever you initialize class.

Syntax:

class className {
  constructor() { ... } //Mandatory Class method
  method1() { ... }
  method2() { ... }
  ...
}

Example:

class Mobile {
  constructor(model) {
    this.name = model;
  }
}

mbl = new Mobile("iPhone");