Advent of Code, Day 2

aoc2.js

import countBy from 'lodash/countBy'

const input = ["kbqwtcvzgumhpwelrnaxydpfuj", "kbqwtcvzgsmhpoelryaxydiqij", "kbqwpcvzssmhpoelgnaxydifuj"] // etc

// pt 1

const charCounts = countBy(input.map(string => string.split(''), char => char))

const {twos, threes} = charCounts.reduce(
  (acc, countObj) => ({
    twos: Object.values(countObj).includes(2) ? acc.twos + 1 : acc.twos,
    threes: Object.values(countObj).includes(3) ? acc.threes + 1 : acc.threes,
  }),
  {
    twos: 0,
    threes: 0,
  }
)

console.log(twos * threes)

// pt 2

const splitStrings = input.map(string => string.split(''))

const collectDifferences = (stringArrA, stringArrB) => {
  return stringArrA.reduce(
    (acc, char, i) => char === stringArrB[i] ? acc : acc.concat([i])
    , []
  );
}
  
const checkAllForMatch = (stringArrA) => {
  let winner;
  let i = 0;

  while (i < splitStrings.length) {
    const result = collectDifferences(stringArrA, splitStrings[i]);
    if (result.length === 1) {
      winner = [stringArrA, result]
    }
    i++
  }
  return winner
};

const checkEachForWinners = () => {
  let winner;
  let i = 0;

  while (!winner) {
    const result = checkAllForMatch(splitStrings[i])
    if (result) {
      winner = result;
    }
    i++;
  }
  return winner;
}

const results = checkEachForWinners();

results[0].splice(results[1], 1)

console.log(results[0].join(''));