part2.ts

import * as fs from 'fs';

const input = fs
	.readFileSync('input', 'utf8')
	.split('\n')
	.map((line) => line.split(': '));
const testValues = input.map((item) => Number(item[0]));
const equationValues = input.map((item) => item[1].split(' ').map(Number));

const checkEquation = (testValue: number, current: number, equationValues: number[]): boolean => {
	if (current > testValue) return false;
	const plusResult = current + equationValues[0];
	const multipleResult = current * equationValues[0];
	const concatenateResult = Number(`${current}${equationValues[0]}`);
	if (equationValues.length === 1) {
		return (
			plusResult === testValue || multipleResult === testValue || concatenateResult === testValue
		);
	}
	const newEquationValues = equationValues.slice(1);
	return (
		checkEquation(testValue, plusResult, newEquationValues) ||
		checkEquation(testValue, multipleResult, newEquationValues) ||
		checkEquation(testValue, concatenateResult, newEquationValues)
	);
};

let result = 0;
for (let i = 0; i < testValues.length; i++) {
	if (checkEquation(testValues[i], equationValues[i][0], equationValues[i].slice(1))) {
		result += testValues[i];
	}
}

console.log(result);