Question 1

How did CS Jackie solve Advent of Code 2024 Day 3 Part 1 in Python?

Accepted Answer

For Part 1, I used Python regex to find every valid mul(x,y) instruction hidden inside the junk memory. I wrote a pattern that extracts the two numbers directly, then I loop through the returned tuples, multiply x*y, and add everything into a running total. It’s basically “findall → multiply → sum,” just with the pain of regex on top.

Question 2

What regex pattern did you use to extract the numbers from mul(x,y)?

Accepted Answer

I built a regex that matches the mul(… , …) structure and uses capture groups so I get the digits back rather than the raw matched string. That way, re.findall returns a list of (x, y) tuples that I can iterate over immediately. I leaned on the usual regex resources to tweak the pattern into the “extract groups” version.

Question 3

Why was Advent of Code Day 3 harder than the previous days for you?

Accepted Answer

Day 3 felt more complicated to me because it’s regex-heavy, and I hate doing regex. The input is just a wall of corrupted characters with tiny valid patterns embedded inside it, so it’s easy to miss edge cases. Also, the Part 2 rules change the whole interpretation of the data.

Question 4

How do the do and don’t instructions work in Day 3 Part 2?

Accepted Answer

In Part 2, multiplications are enabled by default at the start of the file. When the memory contains do, every mul(x,y) after that should count; when it contains don’t, every mul(x,y) after that should not count. So you’re basically toggling whether multiplications contribute to the final sum as you scan through the data.

Question 5

What was your approach for Advent of Code Day 3 Part 2, and why didn’t it work?

Accepted Answer

My idea was to filter out the disabled regions first, leaving only the parts that should be active, and then reuse the Part 1 multiplication-summing logic. I split each row by do, then split those segments by don’t and only kept the first chunk (the part before don’t). It looked right even when I debugged it, but I still didn’t get the correct answer, so something subtle is off.

Question 6

What does the input look like for Advent of Code 2024 Day 3?

Accepted Answer

It’s basically corrupted text—random characters everywhere—with occasional valid mul(x,y) patterns hidden inside. Your job is to ignore everything else and only act on the real multiplication instructions. In Part 2, you also have to pay attention to do and don’t appearing in the same messy stream.

Question 7

What functions did you write for this solution?

Accepted Answer

I wrote a small helper to read the input file, then a function to sum multiplications for Part 1. For Part 2, I made a second function that does the same summing but expects the memory to be filtered first based on the activation rules. The overall structure is pretty simple—the complexity is all in parsing correctly.

ADVENT OF CODE 2024 | DAY 3 Jackie's Python Solution

About This Video

Frequently Asked Questions

🎬 More from CS Jackie