Debugging Santa's Memory Meltdown

Simple but fun puzzle today!

The input is a string with a bunch of mul(N,M) blocks in it:

x**mul(2,4)**%&mul[3,7]!@^do_not_**mul(5,5)**+mul(32,64]then(**mul(11,8)****mul(8,5)**)

The goal is to

• find the valid ones, that is blocks containing invalid characters and with numbers between 1 and 3 digits,
• execute the multiplication,
• sum the results.

My solution involved a simple regex function finding all valid mul(N,M) instances:

function getMulExpressions(input: string) {
    return input.match(/mul\([0-9]{1,3},[0-9]{1,3}\)/g);
}

Then a loop to parse the numbers and multiply them:

lines.forEach((line) => {
    const matches = getMulExpressions(line);

    matches?.forEach((match) => {
        const parsedMatch = match.replace('mul(', '').replace(')', '');
        const nums: number[] = parsedMatch
            .split(',')
            .map((str) => Number.parseInt(str));
        result += nums[0] * nums[1];
    });
});

Part 2 is similar, except we also need to find do() and don't() blocks: any mul(N,M) after a do() needs including; any after a don't() needs to be skipped.

const matches = input.match(/don't\(\)|do\(\)|mul\([0-9]{1,3},[0-9]{1,3}\)/g);

let enable = true;
const enabledExpressions: string[] = [];

matches?.forEach((match) => {
    if (match === "don't()") {
        enable = false;
        return;
    } else if (match === 'do()') {
        enable = true;
        return;
    } else {
        if (enable) {
            enabledExpressions.push(match);
        }
    }
});

I allowed myself to "cheat" a tiny bit for part 2, since the original input consists of multiple lines, and I was worried that there was going to be some don't() towards the end of a line that would need to carry over the following line. In order to avoid "remembering" the status across lines, I decided to remove the line breaks so that I could process the whole input at ones, without the need to worry about the don't()s carrying over.

Yes, I'm a despicable person because of that - but a despicable person with 6 total stars nonetheless u.u