part2.ts

import * as fs from 'fs';

const input = fs.readFileSync('input', 'utf8').split('\n\n').map((block => {
	const [rawA, rawB, rawPrize] = block.split('\n');
	const [, xA, yA] = rawA.match(/X\+(\d+), Y\+(\d+)/);
	const [, xB, yB] = rawB.match(/X\+(\d+), Y\+(\d+)/);
	const [, xPrize, yPrize] = rawPrize.match(/X=(\d+), Y=(\d+)/);
	return { xA: Number(xA), yA: Number(yA), xB: Number(xB), yB: Number(yB), xPrize: Number(xPrize) + 10000000000000, yPrize: Number(yPrize) + 10000000000000 };
}));

// xPrize = countA * xA + countB * xB
// yPrize = countA * yA + countB * yB
// --
// countB = (xPrize - countA * xA) / xB
// --
// yPrize = countA * yA + (xPrize - countA * xA) / xB * yB
// yPrize = countA * yA + xPrize * yB / xB - countA * xA * yB / xB
// countA = (yPrize - xPrize * yB / xB) / (yA - xA * yB / xB)
// countA = (yPrize * xB - xPrize * yB) / (yA * xB - xA * yB)
const solve = ({ xA, yA, xB, yB, xPrize, yPrize }) => {
	const countA = (yPrize * xB - xPrize * yB) / (yA * xB - xA * yB);
	const countB = (xPrize - countA * xA) / xB;
	if (Math.floor(countA) === countA && Math.floor(countB) === countB) {
		return countA * 3 + countB;
	}
	return 0;
}

let result = input.map(solve).reduce((a, b) => a + b, 0);

console.log(result);