92 lines
2.6 KiB
JavaScript
92 lines
2.6 KiB
JavaScript
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import fs from "fs";
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import { main as PartOneMain } from "./solution_a.mjs";
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/**
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* Main function for Puzzle B
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*
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* @param {string} data - Puzzle input as a single string.
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*/
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async function main(data) {
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/** @type {[partOneResult: number, {invalidTicketIds: number[], myTicket: number[], nearbyTickets: number[][], parsedRules: [keyName: string, [[number, number],[number, number]]][]}]} */
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const [partOneResult, {
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invalidTicketIds,
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myTicket,
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nearbyTickets: unfilteredNearbyTickets,
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parsedRules,
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}] = (await PartOneMain(data));
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console.time("Part 2")
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/** @type {Map<string, Map<number, number>>} */
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const count = new Map();
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const nearbyTickets = unfilteredNearbyTickets.filter(
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(_, i) => !invalidTicketIds.includes(i)
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);
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for (const rule of parsedRules) {
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for (const ticket of nearbyTickets) {
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for (let k = 0; k < ticket.length; k++) {
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if (
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(ticket[k] >= rule[1][0][0] && ticket[k] <= rule[1][0][1]) ||
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(ticket[k] >= rule[1][1][0] && ticket[k] <= rule[1][1][1])
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) {
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const map = count.get(rule[0]) ?? new Map();
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map.set(k, (map.get(k) ?? 0) + 1);
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if (!count.has(rule[0])) count.set(rule[0], map);
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}
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}
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}
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}
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/** @type {string[]} */
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let done = [];
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let currentIndex = NaN;
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let currentKey = "";
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/** @type {Map<string, number[]>} */
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const indices = new Map();
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for (const [countedKey, occurenceCounter] of count.entries()) {
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const occurences = Array.from(occurenceCounter.entries())
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.filter((entry) => entry[1] === Math.max(...occurenceCounter.values()))
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.map((el) => el[0]);
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indices.set(countedKey, occurences);
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if (occurences.length === 1) {
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currentIndex = occurences[0];
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currentKey = countedKey;
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}
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}
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while (true) {
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for (const key of indices.keys()) {
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if (key === currentKey) continue;
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indices.set(
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key,
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indices
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.get(key)
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.filter((possibleIndex) => possibleIndex !== currentIndex)
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);
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}
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done.push(currentKey);
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// Find next key that only has one possible place
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const single = Array.from(indices.entries()).find(
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([key, value]) => !done.includes(key) && value.length === 1
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);
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if (!single) break;
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[currentKey, [currentIndex]] = single;
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}
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let result = 1
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for(const [key, [index]] of indices.entries()) {
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if(!key.startsWith("departure ")) continue
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result *= myTicket[index]
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}
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console.timeEnd("Part 2")
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return [partOneResult, result];
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}
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fs.readFile("input", (err, data) => {
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if (err) throw err;
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main(data.toString()).then(console.log).catch(console.error);
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});
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