aoc21-20.ts

import { List, Map, Set } from "immutable";
import { Advent, arr } from "advent";

const { compute, computeCheck } = await Advent({ day: 20 });

compute(async (input) => {
	// const data = input.tokens(/,/).map(int);
	const [alg, imageStr] = input.all().split("\n\n");
	let image = imageStr.split("\n").map((c) => c.split(""));
	for (let i = 0; i < 50; i++) {
		image = enhance(image, alg, i % 2 == 0 ? "." : "#");
	}
	return image.reduce((acc, line) => acc + line.reduce((a, c) => c === "#" ? a + 1 : a, 0), 0);
}, 2);

function pad(image: string[][], padWith: string) {
	let out = arr(image.length + 2, () => arr(image[0].length + 2, () => padWith));
	for (let i = 0; i < image.length; i++) {
		for (let j = 0; j < image[i].length; j++) {
			out[i + 1][j + 1] = image[i][j];
		}
	}
	return out;
}

function enhance(image: string[][], alg: string, padWith: string) {
	image = pad(pad(image, padWith), padWith);
	let out = arr(image.length, () => arr(image[0].length, () => "."));
	for (let i = 0; i < image.length; i++) {
		for (let j = 0; j < image.length; j++) {
			let val = 0;
			for (let di of [-1, 0, 1]) {
				for (let dj of [-1, 0, 1]) {
					val *= 2;
					if (
						i + di >= 0 &&
						i + di < image.length &&
						j + dj >= 0 &&
						j + dj < image[i].length
					) {
						if (image[i + di][j + dj] === "#") {
							val++;
						}
					} else if (padWith === "#") {
						val++;
					}
				}
			}
			out[i][j] = alg[val];
		}
	}
	return out;
}

function show(image: string[][]) {
	console.log("\n".repeat(3));
	for (let line of image) {
		console.log(line.join(""));
	}
}

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