day06.js

const fs = require('fs').promises;

(async () => {
  console.log(`Reading input from ${__dirname}/${process.argv[2]}.txt`);
  const inputData = await fs.readFile(`${__dirname}/${process.argv[2]}.txt`);
  const inputs = inputData
    .toString()
    .split('\n\n')
    .filter((b) => b);

  let count1 = 0;
  let count2 = 0;
  inputs.forEach((group) => {
    const groupAnswers = {};
    const groupNum = group.split('\n').filter((c) => c).length;

    group
      .replaceAll('\n', '')
      .split('')
      .forEach((ans) => {
        if (groupAnswers[ans]) {
          groupAnswers[ans]++;
        } else {
          groupAnswers[ans] = 1;
        }
      });

    count2 += Object.keys(groupAnswers).reduce((count, ans) => {
      return groupAnswers[ans] === groupNum ? count + 1 : count;
    }, 0);
    count1 += Object.keys(groupAnswers).length;
  });
  console.log('count1', count1);
  console.log('count2', count2);

  let refactor1 = 0;
  let refactor2 = 0;
  inputs.forEach((group) => {
    const numGroup = group.split('\n').filter((c) => c).length;
    const groupSet = group
      .split('\n')
      .filter((c) => c)
      .map((p) => new Set([...p.split('')]))
      .reduce((c, l) => {
        return new Set([...c.values(), ...l.values()]);
      }, new Set());

    refactor1 += groupSet.size;
  });

  console.log('refactor1', refactor1);
})();