Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Economics & Finance
In JavaScript, you can sum duplicate elements by counting their occurrences and multiplying each unique value by its count. This technique is useful for consolidating arrays with repeated values. For example, if the input array is: const input = [1, 3, 1, 3, 5, 7, 5, 4]; The output should be: [2, 6, 10, 7, 4] This means: 1 appears 2 times (1×2=2), 3 appears 2 times (3×2=6), 5 appears 2 times (5×2=10), while 7 and 4 appear once each. Using Map to Count and Sum The most efficient ... Read More
JavaScript's localStorage provides a simple way to store data persistently in the user's browser. Use localStorage.setItem() to store values and localStorage.getItem() to retrieve them. Syntax // Set a value localStorage.setItem("keyName", "value"); // Get a value let value = localStorage.getItem("keyName"); // Remove a value localStorage.removeItem("keyName"); // Clear all localStorage data localStorage.clear(); Setting Values in localStorage The setItem() method accepts two parameters: a key name and the value to store. Values are always stored as strings. ... Read More
Deep searching a JSON object means recursively traversing through all nested objects and arrays to find elements that match specific criteria. This is useful when you need to locate objects buried deep within complex data structures. The Problem Suppose we have the following nested JSON object: const obj = { id: 1, title: 'hello world', child: { id: null, title: 'foobar', ... Read More
An identity matrix is a square matrix where all diagonal elements are 1 and all other elements are 0. This type of matrix is fundamental in linear algebra and has the property that when multiplied with any matrix, it returns the original matrix unchanged. What is an Identity Matrix? An identity matrix of order n is an n × n square matrix where: All diagonal elements (where row index equals column index) are 1 All other elements are 0 For example, an identity matrix of order 3 will be: [ [1, ... Read More
In JavaScript, a Kit-Kat array is a custom array where numbers are replaced with specific strings based on divisibility rules. This pattern is similar to the classic FizzBuzz problem but with customizable divisors. Problem Statement Create a function that takes three parameters: a natural number num, and two divisors m and n. The function should return an array containing numbers from 1 to num with these replacements: Replace multiples of m with 'kit' Replace multiples of n with 'kat' Replace multiples of both m ... Read More
We need to create a JavaScript function that takes two arrays of single-digit numbers and returns a new array representing the maximum possible number of a specified length. The function must preserve the relative order of elements from each original array. Problem Statement Given two arrays representing numbers and a target length num, we need to: Select digits from both arrays to form the largest possible number Maintain the relative order within each array Return exactly num digits Example Input and Output const arr1 = [1, 3, 4, 5, 6]; const arr2 ... Read More
Problem We are required to write a JavaScript function that takes in an array of numbers of length at least three. Our function should simply return the third smallest number from the array. Example Following is the code − const arr = [6, 7, 3, 8, 2, 9, 4, 5]; const thirdSmallest = () => { const copy = arr.slice(); for(let i = 0; i < 2; i++){ const minIndex = copy.indexOf(Math.min(...copy)); copy.splice(minIndex, ... Read More
Problem We are required to write a JavaScript function that takes in a string number as the only argument. Our function should return the input number with the second half of digits changed to 0. In cases where the number has an odd number of digits, the middle digit onwards should be changed to 0. For example: 938473 → 938000 How It Works The algorithm works by calculating the midpoint of the string. For even-length strings, exactly half the digits are preserved. For odd-length strings, the middle digit becomes part of ... Read More
Given a non-negative integer, we need to write a function that returns an array containing the digits in reverse order. This is a common programming challenge that demonstrates string manipulation and array operations. Example 348597 => The correct solution should be [7, 9, 5, 8, 4, 3] Method 1: Using String Split and Reverse The most straightforward approach is to convert the number to a string, split it into individual characters, reverse the array, and convert back to numbers: const num = 348597; const reverseArrify = num => { ... Read More
Finding the middle element of an array is a common programming task in JavaScript. The approach differs depending on whether the array has an odd or even number of elements. Array Basics An Array in JavaScript is a data structure used to store multiple elements. These elements are stored at contiguous memory locations and accessed using index numbers starting from 0. Syntax const array_name = [item1, item2, ...]; Example of array declaration: const body = ['Eyes', 'Nose', 'Lips', 'Ears']; Understanding Middle Element Logic Finding the middle element depends ... Read More