ProblemWe are required to write a JavaScript function that takes in an array of sorted integers, arr, as the first and the only argument.Our function should return true if and only if we can split the array into 1 or more subsequences such that each subsequence consists of consecutive integers and has length at least 3, false otherwise.For example, if the input to the function isInputconst arr = [1, 2, 3, 3, 4, 5];Outputconst output = true;Output ExplanationWe can split them into two consecutive subsequences −1, 2, 3 3, 4, 5ExampleFollowing is the code − Live Democonst arr = [1, 2, ... Read More

Increasing SequenceWe define an array as increasing if arr[i]

ProblemWe are required to write a JavaScript function that takes in an array of numbers, arr, as the first and the only argument.Our function is required to find the number of longest increasing subsequences (contiguous or non-contiguous).For example, if the input to the function isInputconst arr = [2, 4, 6, 5, 8];Outputconst output = 2;Output ExplanationThe two longest increasing subsequences are [2, 4, 5, 8] and [2, 4, 6, 8].ExampleFollowing is the code − Live Democonst arr = [2, 4, 6, 5, 8]; const countSequence = (arr) => {    const distance = new Array(arr.length).fill(1).map(() => 1)    const count = ... Read More

ProblemWe are required to implement a MapSum class with insert, and sum methods. For the method insert, we'll be given a pair of (string, integer). The string represents the key and the integer represents the value. If the key already existed, then the original key-value pair will be overridden to the new one.For the method sum, we'll be given a string representing the prefix, and we need to return the sum of all the pairs' values whose key starts with the prefix.ExampleFollowing is the code − Live Democlass Node {    constructor(val) {       this.num = 0     ... Read More

ProblemWe are required to write a JavaScript function that takes in an array of exactly 4 numbers, arr, as the first argument and a target as the second argument.Our function need to judge whether the numbers in the array arr could operated through *, /, +, -, (, ) to get the value equal to target.For example, if the input to the function isInputconst arr = [5, 3, 2, 1]; const target = 4;Outputconst output = true;Output ExplanationBecause we can achieve 4 like this −(5 - 1) * (3 - 2) = 4ExampleFollowing is the code − Live Democonst arr = ... Read More

ProblemWe are required to write a JavaScript function that takes in a string, str, as the first and the only argument.Our function may delete at most one character from the string str and we are required to check whether we can make it a palindrome doing so.For example, if the input to the function isInputconst str = 'dr.awkward';Outputconst output = true;Output ExplanationBecause if we delete ‘.’ from the string,ExampleFollowing is the code − Live Democonst str = 'dr.awkward'; const validPalindrome = (str = '') => {    const valid = (left, right) => {          for (let i = left; i

ProblemWe are required to write a JavaScript function that takes in a string, time, that represents time in the "HH:MM" form.Our function is supposed to form the next closest time by reusing the current digits. There is no limit on how many times a digit can be reused.For example, if the input to the function isInputconst time = '19:34';Outputconst output = '19:39';Output ExplanationThe next closest time choosing from digits 1, 9, 3, 4, is 19:39, which occurs 5 minutes later. It is not 19:33, because this occurs 23 hours and 59 minutes later.ExampleFollowing is the code − Live Democonst time = ... Read More

ProblemWe are required to write a JavaScript function that takes in two strings, str1 and str2, as the first and the second argument.Our function should return the minimum number of times we should repeat string str1 so that string str2 is a substring of it. If it is impossible for str2 to be a substring of a after repeating it, we should return -1For example, if the input to the function isInputconst str1 = 'wxyz'; const str2 = 'yzwxyzwx';Outputconst output = 3;Output ExplanationWe return 3 because by repeating a three times "abcdabcdabcd", b is a substring of it.ExampleFollowing is the ... Read More

ProblemWe are required to write a JavaScript function that takes in an array, arr, of strings of English lowercase alphabets as the first argument. The second argument to our function is a number, num (num < length of arr).Our function is supposed to return the num most frequent elements in the array arr.The answer should be sorted by frequency from highest to lowest. If two words have the same frequency, then the word with the lower alphabetical order comes first.For example, if the input to the function isInputconst arr = ["the", "day", "is", "sunny", "the", "the", "the", "sunny", "is", "is"]; ... Read More

ProblemWe are required to write a JavaScript function that takes in an integer, num, as the first and the only argument.Our function should check whether the binary representation of num has alternating bits − namely, if two adjacent bits will always have different values.For example, if the input to the function isInputconst num = 5;Outputconst output = true;Output ExplanationBecause the binary form of 5 is 101 which have alternating bits.ExampleFollowing is the code − Live Democonst num = 5; const isAlternating = (num = 1) => {    const binary = num.toString(2);    let curr = binary[0];    for(let i = ... Read More