e-mihaylin

const angle = (a, b, c ,d) => ~~((Math.atan2(d - b, c - a)) * 180 / Math.PI);

e-mihaylin

/**
 * [1,2,3].equals([1,2,3]); // true
 * [1,2,3].equals([1,2]); // false
 * [1,2,3].equals([1,2,4]); // false
 * [1,2,3].equals("123"); // false
 * Array.prototype.equals.call("123", "123"); // true
 * Array.prototype.equals.call("123", [1,2,3]); // false
 * [1,2,3].equals([1,2,{value: 3}], (x, y) => (x.value || x) === (y.value || y)); // true
 */
Array.prototype.equals = function (other, callback = (x, y) => (x === y)) {

e-mihaylin

const decodeMorse = morseCode => morseCode
  .trim()
  .split` `
  .map(e => morseDictionary[e])
  .join``
  .replace(/\s+/g, ' ');

const morseDictionary = {
  '...---...': 'SOS',
  '-.-.--': '!',

e-mihaylin

function regexDivisibleBy(n) {
  if (n==1) return '^[01]+$'  // Special case
  let a = []  // List of nodes
  for (let i=0; i<n; i++) a[i] = {}  // Node
  for (let i=0; i<n; i++) {
    a[i].id = i            // Used for indentification below
    a[i][i*2%n] = '0'      // Keys in nodes are id refs to other nodes
    a[i][(i*2+1)%n] = '1'  // Values in nodes are the required chars to get to next node (the key)
  }
  

e-mihaylin

const regexDivisibleBy = n => {
  if (n == 1) return '^(0|1)+$';
  if (n == 2) return '^(0|1)+0$';
  if (n == 3) return '^(0*(1(01*0)*1)*)*$';
  if (n == 4) return '^(0|1)+00$';
  if (n == 5) return '^(0|1(10)*(0|11)(01*01|01*00(10)*(0|11))*1)+$';
  if (n == 6) return '^(0|(11|1(00|011*0)(00|011*0)*1)(11|1(00|011*0)(00|011*0)*1)*0)+$';
  if (n == 7) return '^(0|(10((0|11)(1|00))*(10|(0|11)01)|11)(01*0(0|101|1(1|00)((0|11)(1|00))*(10|(0|11)01)))*1)+$';
  if (n == 8) return '^(0|1)+000$';
}

e-mihaylin

const determinant = m => {
  const l = m.length;
  if (l === 1) return m[0][0];
  if (l === 2) return m[0][0] * m[1][1] - m[1][0] * m[0][1];

  let result = 0;
  for (let i = 0; i < l; i++) {
    result += Math.pow(-1, i) * m[0][i] * determinant(minor(m, i, 0));
  }
  return result;

e-mihaylin

const parseInt = string => {
  var n = 0, 
      g = 0;
  
  function text2num(s) {
    const a = s.toString().split(/[\s-]+/);
    a.forEach(feach);
    return n + g;
  }
  

e-mihaylin

const RomanNumerals = {
  toRoman: v => {
    let s = '';
    RomanNumerals.numerals.forEach(n => {
      while (v >= n[1]) {
        s += n[0];
        v -= n[1]; 
      }
    });
    return s;

e-mihaylin

function toChineseNumeral(num) {
  var numerals = {
    "-":"负",
    ".":"点",
    0:"零",
    1:"一",
    2:"二",
    3:"三",
    4:"四",
    5:"五",

e-mihaylin

function add() {
  var c = 1000000000;
  var args = Array.prototype.slice.call(arguments);
  var sum = 0;
  for (var i = 0; i < args.length; i++) sum += args[i] * c;
  return (sum / c).toString();  
}