Advent of Code - Day 4: The Ideal Stocking Stuffer

aoc4.js

import MD5 from 'crypto-js/md5';

const findNumberForPrefixedMD5 = (str, prefix = '00000') => {
  let i = 0;
  let hash;
  do {
    i += 1;
    hash = MD5(str + i).toString();
  } while (!hash.startsWith(prefix));
  return i;
};

const expect = (actual, expected) => {
  if (actual !== expected) {
    console.error(`Expected ${expected} got ${actual}`);
    return false;
  }
  return true;
};

const tests = [
  ['abcdef', 609043],
  ['pqrstuv', 1048970]
].map(([str, expected]) => {
  return expect(findNumberForPrefixedMD5(str), expected);
});

if (tests.every(Boolean)) console.log('All tests passed!');