AdventOfCode2020/day_4/task_1.js

const fs = require('fs');
const file = fs.readFileSync(__dirname + '/input.txt').toString('utf-8');
const passports = file.split('\n\n');

const fieldNames = {
    byr: 'Birth year',
    iyr: 'Issue year',
    eyr: 'Expiration year',
    hgt: 'Height',
    hcl: 'Hair color',
    ecl: 'Eye color',
    pid: 'Passport ID',
    cid: 'Country ID'
}, passportFields = Object.keys(fieldNames);

const bypassed = [ 'cid' ]; // These are ignored

let invalid = 0;
let invalidStats = {}
passportFields.forEach(field => invalidStats[field] = 0);

passports.forEach(passport => {
    passport = passport
        .replace(/\n/g, ' ')
        .split(' ');
    
    let inv = false;
    passportFields.forEach(field => {
        let h = passport.filter(h => h.split(':')[0] == field);
        if (h?.[0]) h = h[0].split(':');
        if (!h[1] && bypassed.indexOf(field) == -1) {
            inv = true;
            invalidStats[field] += 1;
        }
    });
    if (inv) invalid++;
});

let statsStr = ``; 
for (const [key, value] of Object.entries(invalidStats))
    statsStr += `${fieldNames[key]}: ${value}\n`;

console.log(statsStr);
console.log(`Invalid passports: ${invalid}`);
console.log(`Valid passports: ${passports.length - invalid}`);
console.log(`Total passports: ${passports.length}`);