AdventOfCode2020/day_2/task_1.js

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

let invalid = []

arr.forEach(item => {
    // Split the puzzle input
    let split = item.split(": ");
    let pw = split[1];
    
    split = split[0].split(" ");
    let wantedLetter = split[1];
    
    split = split[0].split("-");
    let [lowerNum, upperNum] = split;
    
    // Check if the password is valid
    let count = 0;
    for (let letter of pw) {
        if (letter == wantedLetter) count++;
    }
    
    if (count < lowerNum || count > upperNum) {
        invalid.push(pw);
    }
});

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