part2.ts

import * as fs from 'fs';

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

let path: string[] = [];
const dirs: Record<string, number> = {};

for (const line of input) {
	let _a, _b;

	let dirName = (_a = line.match(/\$ cd ([\w\/.]+)/)) === null || _a === void 0 ? void 0 : _a[1];
	if (dirName === '/') {
		path = [''];
		continue;
	} else if (dirName === '..') {
		path.pop();
		continue;
	} else if (dirName) {
		path.push(dirName);
		continue;
	}

	let size = (_b = line.match(/(\d+) .+/)) === null || _b === void 0 ? void 0 : _b[1];
	if (size) {
		path.forEach((dir, i) => {
			var key = path.slice(0, i).join('/') + '/' + dir;
			dirs[key] ??= 0;
			dirs[key] += Number(size);
		});
		continue;
	}
}

let result = undefined;
const availableSpace = 70000000 - dirs['/'];
const spaceToFree = 30000000 - availableSpace;
Object.values(dirs).forEach((size) => {
	if (size >= spaceToFree && (!result || size < result)) {
		result = size;
	}
});

console.log(result);