amejiarosario

powerset('') // ...
// n = 0, f(n) = 1;
powerset('a') // , a...
// n = 1, f(n) = 2;
powerset('ab') // , a, b, ab...
// n = 2, f(n) = 4;
powerset('abc') // , a, b, ab, c, ac, bc, abc...
// n = 3, f(n) = 8;
powerset('abcd') // , a, b, ab, c, ac, bc, abc, d, ad, bd, abd, cd, acd, bcd...
// n = 4, f(n) = 16;

amejiarosario

function powerset(n = '') {
  const array = Array.from(n);
  const base = [''];

  const results = array.reduce((previous, element) => {
    const previousPlusElement = previous.map(el => {
      return `${el}${element}`;
    });
    return previous.concat(previousPlusElement);
  }, base);

amejiarosario

function hasDuplicates(n) {
  const duplicates = [];
  let counter = 0; // debug

  for (let outter = 0; outter < n.length; outter++) {
    for (let inner = 0; inner < n.length; inner++) {
      counter++; // debug

      if(outter === inner) continue;

amejiarosario

powerset('') // =>  ['']
powerset('a') // => ['', 'a']
powerset('ab') // => ['', 'a', 'b', 'ab']

amejiarosario

/**
 * Sort array in asc order using merge-sort
 * @example
 *    sort([3, 2, 1]) => [1, 2, 3]
 *    sort([3]) => [3]
 *    sort([3, 2]) => [2, 3]
 * @param {array} array
 */
function sort(array = []) {
  const size = array.length;

amejiarosario

function indexOf(array, element, offset = 0) {
  // split array in half
  const half = parseInt(array.length / 2);
  const current = array[half];

  if(current === element) {
    return offset + half;
  } else if(element > current) {
    const right = array.slice(half);
    return indexOf(right, element, offset + half);

amejiarosario

function findXYZ(n) {
  const solutions = [];

  for(let x = 0; x < n; x++) {
    for(let y = 0; y < n; y++) {
      for(let z = 0; z < n; z++) {
        if( 3*x + 9*y + 8*z === 79 ) {
          solutions.push({x, y, z});
        }
      }

amejiarosario

function sort(n) {
  for (let outer = 0; outer < n.length; outer++) {
    let outerElement = n[outer];

    for (let inner = outer + 1; inner < n.length; inner++) {
      let innerElement = n[inner];

      if(outerElement > innerElement) {
        // swap
        n[outer] = innerElement;

amejiarosario

function hasDuplicates(n) {
  const duplicates = [];

  for (let outter = 0; outter < n.length; outter++) {
    for (let inner = 0; inner < n.length; inner++) {
      if(outter === inner) continue;

      if(n[outter] === n[inner]) {
        return true;
      }

amejiarosario

function findMax(n) {
  let max;
  let counter = 0;
  for (let i = 0; i < n.length; i++) {
    counter++;
    if(max === undefined || max < n[i]) {
      max = n[i];
    }
  }
  return max;