59 lines
1.6 KiB
JavaScript
59 lines
1.6 KiB
JavaScript
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import fs from "fs";
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const CONTENT_REGEX = /^(\d+) (\w+ \w+) bags?.?$/;
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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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* @returns {number} Amount of bags inside a shiny golden bag.
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*/
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async function main(data) {
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const lines = data.split(/\r?\n/);
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/** @type {Object.<string, [number, string][]>} */
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const contentsOf = {};
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/** @type {Object.<string, [number, string][]>} */
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const containedBy = {};
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for (const line of lines) {
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const [bag, content] = line.split(" bags contain ");
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contentsOf[bag] = [];
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if (content === "no other bags.") continue;
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contentsOf[bag] = content.split(", ").map((entry) => {
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const [, count, containedBag] = entry.match(CONTENT_REGEX);
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return [parseInt(count), containedBag];
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});
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for (const [count, containedBag] of contentsOf[bag]) {
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if (!containedBy.hasOwnProperty(containedBag))
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containedBy[containedBag] = [];
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containedBy[containedBag].push([count, bag]);
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}
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}
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/**
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* @param {string} bag Bag to count contents of.
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* @returns {number} Total amount of bags inside bag, recursively.
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*/
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function countBags(bag) {
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if (!contentsOf.hasOwnProperty(bag)) {
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return 0;
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}
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const contents = contentsOf[bag];
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let result = contents.reduce((prev, cur) => prev + cur[0], 0);
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result += contents.reduce(
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(prev, cur) => prev + cur[0] * countBags(cur[1]),
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0
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);
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return result;
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}
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return countBags("shiny gold");
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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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