part2.ts

import * as fs from 'fs';

const input = fs.readFileSync('input', 'utf8').split('\n');

const RESOURCE_MAP = { ore: 0, clay: 1, obsidian: 2, geode: 3 };
type ElementType = keyof typeof RESOURCE_MAP;

const blueprints = input.map((line: string) => {
	let [, plans] = line.split(': ');
	return plans.split('. ').map((line: string) => {
		const [, cost] = line.match(/^Each [^\s]+ robot costs ([^.]*)\.?$/)!;
		const requirements = [0, 0, 0, 0];
		cost.split(' and ').forEach((s) => {
			const [resourceCount, resourceType] = s.split(' ') as [string, ElementType];
			requirements[RESOURCE_MAP[resourceType]] = +resourceCount;
		});
		return requirements;
	});
}) as number[][][];

const best = (blueprint: number[][], timeAvailable: number) => {
	const queue = [
		{
			resources: [0, 0, 0, 0],
			robots: [1, 0, 0, 0],
			time: timeAvailable,
		},
	];
	let max = 0;
	const maxNeeded = [
		//completely bogus heuristic
		Math.max(...blueprint.map((cost) => cost[0])) * 1.5,
		Math.max(...blueprint.map((cost) => cost[1])) * 1.5,
		Math.max(...blueprint.map((cost) => cost[2])) * 1.5,
		Infinity,
	];
	while (queue.length > 0) {
		const next = queue.pop();
		let { resources, robots, time } = next!;
		max = Math.max(max, resources[3] + robots[3] * time);

		blueprint.forEach((requirements, robotType) => {
			let buildTime = 1;
			requirements.forEach((cost, r) => {
				const timeForResource = Math.ceil((cost - resources[r]) / robots[r]);
				if (cost > 0) buildTime = Math.max(buildTime, timeForResource + 1);
			});
			if (buildTime < time && resources[robotType] <= maxNeeded[robotType]) {
				const nextResources = [...resources];
				const nextRobots = [...robots];
				requirements.forEach((cost, r) => {
					nextResources[r] += robots[r] * buildTime - cost;
				});
				nextRobots[robotType]++;
				queue.push({
					resources: nextResources,
					robots: nextRobots,
					time: time - buildTime,
				});
			}
		});
	}
	return max;
};

let score = 1;
blueprints.slice(0, 3).forEach((blueprint) => {
	score *= best(blueprint, 32);
});

console.log(score);