aoc21-14.ts

import { Map } from 'immutable';
import { Advent, arr, int } from "advent";

const { compute, computeCheck } = await Advent({ day: 14 });

compute(async (input) => {
	// const data = input.tokens(/,/).map(int);
	// const data = input.ints();
	const [start, rules] = input.all().split("\n\n");

	let ruleMap = Map<string, string>();
	for (let rule of rules.split("\n")) {
		let [pattern, result] = rule.split(" -> ");
		ruleMap = ruleMap.set(pattern, result);
	}

	console.log(ruleMap.toJSON());

	let pat = Map<string, number>();

	for (let i = 0; i < start.length - 1; i++) {
		pat = pat.update(start[i] + start[i + 1], 0, (v) => v + 1);
	}

	for (let i = 0; i < 40; i++) {
		pat = step(pat, ruleMap);
	}

	let outMap = Map<string, number>();
	outMap = outMap.update(start[0], 0, (v) => v + 1);
	outMap = outMap.update(start[start.length - 1], 0, (v) => v + 1);

	for (let [k, c] of pat) {
		outMap = outMap.update(k[0], 0, (v) => v + c);
		outMap = outMap.update(k[1], 0, (v) => v + c);
	}

	let min = outMap.minBy((v) => v)!;
	let max = outMap.maxBy((v) => v)!;

	return (max - min) / 2;
}, 2);

function step(pattern: Map<string, number>, rules: Map<string, string>): Map<string, number> {
	let out = Map<string, number>();

	for (let [key, cnt] of pattern) {
		if (rules.has(key)) {
			out = out.update(key[0] + rules.get(key)!, 0, (v) => v + cnt);
			out = out.update(rules.get(key)! + key[1], 0, (v) => v + cnt);
		}
	}

	return out;
}

// computeCheck(async function* (input) {
// 	yield 0;
// });