We are required to write a JavaScript function that takes in an array of Integers. The function should return the length of the longest decreasing subsequence from the array.For example −If the input array is −const arr = [5, 2, 5, 4, 3, 2, 4, 6, 7];Then the output should be −const output = 4;because the longest decreasing subsequence (of consecutive words) is [5, 4, 3, 2];Exampleconst arr = [5, 2, 5, 4, 3, 2, 4, 6, 7]; const decreasingSequence = (arr = []) => {    let longest = [];    let curr = [];    const setDefault = ... Read More

We are required to write a JavaScript function that in any number of arguments (all of Number type).The function should calculate all possible sums of addition and subtraction.For example − If the arguments are 1, 2, 3Then all possible combinations are −1 + 2 + 3 1 - 2 - 3 1 + 2 - 3 1 - 2 + 3Finally, the function should the sum that is closest to 0. In this case, that answer would just be 0.Exampleconst findSmallestPositive = (...arr) => {    let set = new Set([Math.abs(arr[0])]);    for (let i = 1;    i < ... Read More

We are required to write a JavaScript function that takes in a read only array of n + 1 integers between 1 and n.The function should find one number that repeats in linear time and using at most O(n) space.For example If the input array is −const arr = [3 4 1 4 1];Then the output should be −const output = 1;If there are multiple possible answers ( like above ), we should output any one. If there is no duplicate, we should output -1.Exampleconst arr = [3, 4, 1, 4, 1]; const findRepeatedNumber = (arr = []) => { ... Read More

In this article, we will learn to implement Quicksort recursively in JavaScript. Quicksort is one of the most efficient and widely used sorting algorithms, known for its divide-and-conquer approach. What is Quicksort? Quicksort is a divide-and-conquer sorting algorithm that sorts an array by selecting a pivot element and partitioning the array into two subarrays: elements smaller than the pivot and elements greater than or equal to the pivot. It then recursively sorts the subarrays.  Algorithm Quicksort follows the below steps − Step 1 − Make any element the pivot (preferably first or last, ... Read More

Suppose, we have an array that contains some demo credit card numbers like this −const arr = ['4916-2600-1804-0530', '4779-252888-3972', '4252-278893-7978', '4556-4242-9283-2260'];We have been tasked with creating a function that takes in this array. The function must return the credit card number with the greatest sum of digits.If two credit card numbers have the same sum, then the last credit card number should be returned by the function.ExampleThe code for this will be −const arr = ['4916-2600-1804-0530', '4779-252888-3972', '4252-278893-7978', '4556-4242-9283-2260']; const findGreatestNumber = (arr) => {    let n, i = 0, sums;    sums = [];    while (i < ... Read More

Suppose, we have the following array of objects −const arr = [    {"2015":11259750.05},    {"2016":14129456.9} ];We are required to write a JavaScript function that takes in one such array. The function should prepare an array of arrays based on the input array.Therefore, the output for the above array should look like −const output = [    [2015,11259750.05],    [2016,14129456.9] ];ExampleThe code for this will be −const arr = [    {"2015":11259750.05},    {"2016":14129456.9} ]; const mapToArray = (arr = []) => {    const res = [];    arr.forEach(function(obj,index){       const key= Object.keys(obj)[0];       const value = parseInt(key, 10);       res.push([value, obj[key]]);    });    return res; }; console.log(mapToArray(arr));OutputAnd the output in the console will be −[ [ 2015, 11259750.05 ], [ 2016, 14129456.9 ] ]

We are required to write a JavaScript program that provides users an input to fill in a number.And upon filling when the user clicks the button, we should display the sum of all the digits of the number.ExampleThe code for this will be −JavaScript Code −function myFunc() {    var num = document.getElementById('digits').value;    var tot = 0;    num.split('').forEach( function (x) {       tot = tot + parseInt(x,10);    }); document.getElementById('output').innerHTML = tot; }HTML Code − Submit OutputAnd the output will be &miuns;After clicking “Submit” −

We have a mixed array that we need to sort by alphabet and then by digit −const arr = ['Ab-1', 'Ab-11', 'Ab-12', 'ab-10', 'ab-100', 'ab-101', 'ab2', 'ab-3', 'ab-105'];ExampleThe code for this will be −const arr = ['Ab-1', 'Ab-11', 'Ab-12', 'ab-10', 'ab-100', 'ab-101', 'ab2', 'ab-3', 'ab-105']; const alphaNumericSort = (arr = []) => {    arr.sort((a, b) => {       const aPart = a.split('-');       const bPart = b.split('-');       return aPart[0].toLowerCase().localeCompare(bPart[0].toLowerCase()) || aPart[1] - bPart[1];    }); }; alphaNumericSort(arr); console.log(arr);OutputAnd the output in the console will be −[    'Ab-1', 'ab-2',    'ab-3', 'ab-10', ... Read More

Suppose, we have a 2-D array like this −const arr = [    [3, 1],    [2, 12],    [3, 3] ];We are required to write a JavaScript function that takes in one such array.The function should then create a new 2-D array that contains all elements initialized to undefined other than the element's index present in the input array.Therefore, for the input array, output[3][1] = 1; output[2][12] = 1; output[3][3] = 1;And rest all elements should be initialized to undefinedTherefore, the final output should look like −const output = [    undefined,    undefined,    [       ... Read More

Suppose we have the following array of objects −const arr = [    {       'name' : 'd',       'index' : 3    },    {       'name' : 'c',       'index' : 2    },    {       'name' : 'a',       'index' : 0    },    {       'name' : 'b',       'index' : 1    } ];We are required to write a JavaScript function that takes in one such array.The function should sort this array in increasing order according to ... Read More