Advent of Code 2024 Day 3

— Day 3: Mull It Over —

We need to multiply some numbers from corrupted computer memory.

Scan the corrupted memory for uncorrupted mul instructions. What do you get if you add up all of the results of the multiplications?

with open('data-2024-03.txt', 'r') as f:
    inp = f.read().splitlines()

Regex, amirite?

import re

patt = r'mul\([0-9]+,[0-9]+\)'

mul_out = []

for i in inp: 
    mul_out += re.findall(patt, i)
    
# mul_out

def get_digi(z): 
    a,b = z.split(',')
    c,d = a.split('(')
    e = b[:-1]
    return int(d) * int(e)


digi = [get_digi(x) for x in mul_out]

# digi

sum(digi)

# 174561379

174561379

— Part Two —

There are some do() and some don't() instructions which turn on and turn off the mul() instructions.

Handle the new instructions; what do you get if you add up all of the results of just the enabled multiplications?

patt = r'mul\([0-9]+,[0-9]+\)|do\(\)|don\'t\(\)'

new_out = []

for i in inp: 
    new_out += re.findall(patt, i)
    
# new_out

nice_out = []

do_dont = True

for n in new_out:
    if n == 'do()': 
        do_dont = True
    elif n == "don't()": 
        do_dont = False
    else: 
        if do_dont: 
            nice_out.append(n)

len(mul_out)
len(new_out)
len(nice_out)
# nice_out

digi = [get_digi(x) for x in nice_out]

# digi

sum(digi)

# 106921067

106921067