aoc23-10.mts

import { Advent, f, fm, chr, ord, mapGrid, neighbors } from "advent";
import { Set, Map } from "immutable";

const { compute, computeCheck } = await Advent({ day: 10 });

compute(2, async (input) => {
	const data = input.parse(f.cGrid());

	let startPosition: [number, number] = [0, 0];

	for (let i = 0; i < data.length; i++) {
		for (let j = 0; j < data[i].length; j++) {
			if (data[i][j] === "S") {
				startPosition = [i, j];
				data[i][j] = "J"; // for my input
			}
		}
	}

	let count = 0;
	let i = startPosition[0];
	let j = startPosition[1];
	let visited = Set<string>(`${i},${j}`);
	let loop = Array.from(new Array(data.length * 2), () => new Array(data[0].length * 2).fill(false));

	while (true) {
		loop[i * 2][j * 2] = true;
		const c = data[i][j];
		const up = c == "|" || c == "L" || c == "J";
		const down = c == "|" || c == "7" || c == "F";
		const left = c == "-" || c == "7" || c == "J";
		const right = c == "-" || c == "L" || c == "F";

		if (up && !visited.has(`${i - 1},${j}`)) {
			loop[i * 2 - 1][j * 2] = true;
			i--;
			visited = visited.add(`${i},${j}`);
			count++;
			continue;
		}

		if (down && !visited.has(`${i + 1},${j}`)) {
			loop[i * 2 + 1][j * 2] = true;
			i++;
			visited = visited.add(`${i},${j}`);
			count++;
			continue;
		}

		if (left && !visited.has(`${i},${j - 1}`)) {
			loop[i * 2][j * 2 - 1] = true;
			j--;
			visited = visited.add(`${i},${j}`);
			count++;
			continue;
		}

		if (right && !visited.has(`${i},${j + 1}`)) {
			loop[i * 2][j * 2 + 1] = true;
			j++;
			visited = visited.add(`${i},${j}`);
			count++;
			continue;
		}

		break;
	}


	for (const line of loop) {
		console.log(line.map((x) => (x ? "X" : " ")).join(""));
	}

	const queue = [[0, 0]];

	while (queue.length > 0) {
		const [i, j] = queue.shift()!;
		for (const pt of neighbors([i, j], false)) {
			const [ii, jj] = pt;
			if (ii >= 0 && jj >= 0 && ii < loop.length && jj < loop[0].length && !loop[ii][jj]) {
				loop[ii][jj] = true;
				queue.push([ii, jj]);
			}
		}
	}

	console.log("\n".repeat(20));


	for (const line of loop) {
		console.log(line.map((x) => (x ? "X" : " ")).join(""));
	}

	let ans = 0;

	for (let i = 0; i < loop.length; i++) {
		for (let j = 0; j < loop[i].length; j++) {
			if (!loop[i][j] && i % 2 == 0 && j % 2 == 0) {
				ans++;
			}
		}
	}

	return ans;
});