aoc/2020/16/part1.js

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2020-12-16 19:15:23 +00:00
// I didn't expect this to be very efficient but it acually was pretty quick
const fs = require('fs');
const [fields, myTicket, nearbyTickets] = fs.readFileSync('./input.txt', 'utf-8').split('\n\n');
// make set of all valid nums
const valid = fields.match(/\d+-\d+/g).reduce((a, v) => {
let [start, end] = v.split('-').map(a=>parseInt(a));
for (let j = start; j <= end; j++) {
a.add(j);
}
return a;
}, new Set())
// get all nums on nearby tickets
const nums = nearbyTickets.match(/\d+/g).map(v => parseInt(v))
// find all the nums that aren't valid, add up the total
let v = nums.filter(num => !valid.has(num)).reduce((a,b)=>a+b,0);
console.log(v)