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Let’s say, we are required to write a recursive function that sums all the elements of an array of Numbers but with a twist and the twist is that the recursive function we write cannot initialize any extra variable (memory).Like we cannot use a variable to store the sum or to keep a count of the index of the array, it all has to be using what we already have.Here’s the solution −We already have an array and can use its first element (i.e., the element at zeroth index to hold the recursive sum).The approach is that we repeatedly pop ... Read More
We are required to write a JavaScript function that takes in a number and returns a boolean based on the fact whether or not it comes in the fibonacci series.For example −If the function call is like this −fibonacci(12); fibonacci(89); fibonacci(55); fibonacci(534);Then the output should be −False true true falseNow, let’s write a recursive solution to this problem −Exampleconst fibonacci = (query, count = 1, last = 0) => { if(count < query){ return fibonacci(query, count+last, count); }; if(count === query){ return true; } return false; }; console.log(fibonacci(12)); console.log(fibonacci(55)); ... Read More
Let’s say, we have two arrays, one contains the correct answer strings of some questions and one contains the answers attempted by a candidate, but somehow the arrays got shuffled and now they don’t have answers in corresponding order. But we can be sure that no two questions had the same answers.Our job now is to write a function that takes these two arrays, checks them for common elements and finds all the common elements between them and then calculates the marks percentage of the candidate based on the count of common answers.Let’s write the code for this function −Exampleconst ... Read More
Let’s say, we have an array of objects like this −Exampleconst arr = [ {text:'use'}, {text: 'secur'}, {text: 'form'}, {text: 'user'}, {text: 'users'}, {text: 'form'}, {text: 'secur'}, {text: 'sec'}, {text: 'users'}, {text: 'secu'}, {text: 'secur'}, {text: 'for'}, {text: 'form'} ]Our job is to write a function that takes in this array and a number n and the function should return an array of n objects which have the longest string value for the text key and all the objects should have a unique value for the text ... Read More
We have to write an array function (Array.prototype.get()) that takes in three arguments first, a number n, second is also a number, say m, (m this.length-1){ return false; }; const res = []; for(let i = ind, j = 0; j < num; i += amount, j++){ if(i > this.length-1){ i = i % this.length; }; if(i < 0){ i = this.length-1; }; res.push(this[i]); }; return res; }; console.log(arr.get(4, 6, 'right')); console.log(arr.get(9, 6, 'left'));OutputThe output in the console will be −[ 6, 7, 0, 1 ] [ 6, 5, 4, 3, 2, 1, 0, 7, 6 ]
Let’s say, we have an array of strings, basically it is an array of number strings like this −const arr = ['3', '3', '55', '23', '67', '43', '12', '67', '87', '12'];We are required to write a JavaScript function that takes in one such array and returns the sum of all elements of this array instead of concatenating the string to one another.Let’s write the code for this function −Exampleconst arr = ['3', '3', '55', '23', '67', '43', '12', '67', '87', '12']; const sumString = arr => { const num = arr.reduce((acc, val) => { const sum ... Read More
Watson gives Sherlock an array A of length N. Then he asks him to determine if there exists an element in the array such that the sum of the elements on its left is equal to the sum of the elements on its right.We have to write this function, it should take in an array of Numbers, and any such number exists in the array, it should return its index, otherwise it should return -1. So, let’s write the code for this function −Exampleconst arr = [1, 2, 3, 4, 5, 7, 3]; const arr2 = [4, 6, 3, 4, ... Read More
Let’s say, we have two objects like these −const a = { Make: "Apple", Model: "iPad", hasScreen: "yes", Review: "Great product!", }; const b = { Make: "Apple", Model: "iPad", waterResistant: false };We are required to write a function that counts the number of common properties in the objects (by common property we mean having both key and value same) and returns a number between 0 and 100 (both inclusive) that represents the percentage of similarity between the objects. Like if no key/value pair matches it will be 0, if all matches it ... Read More
We have an array of Number / String literals that contains some values (some are repetitive as well). Our job is to write a function that returns the element from the array which appears for the greatest number of times in the array.For example − if the input array is −const input = ['a', 'v', 'k', 'f', 'a', 'f', 's', 'd', 'd', 'f', 'a', 'j', 'a'];Then the output should be −'a'because 'a' gets repeated for the maximum number of timesTherefore, let’s write the code for this. We will use a Map() to keep track of all the elements we encounter ... Read More
Let’s say, we have an array with a huge number of Number entries and are required to compare the time recursion takes versus the time a simple loop takes versus the time ES6 function takes in summing all the entries of the array i.e. recursion vs for loop vs ES6 function.Here, to simulate a large array we will iterate over a relatively smaller array for a large number of times (of the order of 10000000). Our main aim is just to have a rough ratio of the time each method takes in summing the array.Part 1: Recursive Approachconst recursiveSum = ... Read More