vadimkorr

//Task: Find the greatest common divisor for an array of integers
//Tags: array, gcd

let arr = [6, 9, 21]

let gcd = function(a, b) {
  a = Math.abs(a)
  b = Math.abs(b)
  while (a != b) {
    if (a > b) a -= b

vadimkorr

// Task: Given array of size 2*N-1, containing N-1 pairs of same integers and one unique integer.
// Find unique integer without sorting array - it's too big
// Complexity: O(n)

let findUnique = function(lst) {
  let map = new Map();
  lst.forEach((id) => {
    if (map.has(id)) map.delete(id);
    else map.set(id, 1);
  })

vadimkorr

// Task: Given an array of N numbers. 
// Find longest subsequence of increasing numbers

let findLongestSubs = function(arr) {
  if (arr.length === 0) {
    return null;
  } else if (arr.length === 1) {
    return arr[0];
  } else {
    let longestLen = 1;

vadimkorr

// Find x^y mod p
// Right-to-left method

let modPow = (x, y, p) => {
  let res = 1;
  x %= p;
  while(y>0) {
    if (y%2 == 1) res = res*x % p
    y = Math.floor(y/2)
    x = x*x % p

vadimkorr

// Find amount of even numbers X in range: A <= X <= B

let find = (a, b) => {
  return Math.floor((b - a) / 2) + (a%2==0 || b%2==0 ? 1 : 0)
}

console.log(find(1, 5)) // 2
console.log(find(1, 4)) // 2
console.log(find(2, 5)) // 2
console.log(find(2, 4)) // 2

vadimkorr

// Find numbers divisible by M in range A <= X <= B

let find = (a, b, m) => {
  a = a%m == 0 ? a : a + m - a%m
  while(a<=b) {
    console.log(a);
    a += m
  }
  console.log("===")
}

vadimkorr

// Calculate fibonacci numbers

let fibRec = (n) => {
  if (n<=1) return n;
  return fibRec(n-1) + fibRec(n-2);
}

let mem = [0, 1];
let fibMem = (n) => {
  if (n<=1) return n;

vadimkorr

// Merge two sorted arrays 

let a = [2, 5, 7, 9, 10]
let b = [1, 3, 8, 10, 11, 15]
let c = []


let i = j =0
while (i < a.length && j < b.length) {
    if(a[i] < b[j]) {

vadimkorr

function dll() {
  this.head = null
}

dll.prototype.push = function(val) {
  let head = this.head, curr = head, prev = head
  if (!head) this.head = { val: val, prev: null, next: null }
  else {
    while (curr && curr.next) {
      prev = curr

vadimkorr

// Insert a number to a sorted linked list with respect to the sorted order

function dll() {
  this.head = null
}

dll.prototype.push = function(val) {
  let head = this.head, curr = head, prev = head
  if (!head) this.head = { val: val, prev: null, next: null }
  else {