aoc2024day3.py

# === Parsing ===

import pathlib

contents = pathlib.Path("input.txt").read_text()

"""
with open("input.txt", "r") as f:
    contents = f.read()
"""

print(contents)


# === Part 1 ===

import re

MUL = r"mul\((\d{1,3}),(\d{1,3})\)"

acc = 0
for match in re.finditer(MUL, contents):
    num1, num2 = match.groups()
    acc += int(num1) * int(num2)

print(acc)


# === Part 2 ===

import re

MATCHES = r"""(?x)
    mul\((\d{1,3}),(\d{1,3})\)  # Finds mul() operations.
    |do\(\)                     # Finds do() “enablers”.
    |don't\(\)                  # Finds don't() “disablers”.
"""

acc = 0
enabled = True
for match in re.finditer(MATCHES, contents):
    if match.group(0) == "do()":
        enabled = True
    elif match.group(0) == "don't()":
        enabled = False
    elif enabled:  # Implicitly, it's a “mul” match.
        num1, num2 = match.groups()
        acc += int(num1) * int(num2)

print(acc)