Advent of Code 2025

“Suddenly, you find yourself in an unfamiliar room! The room has no doors”

“Cephalopod math doesn’t look that different from normal math.”

“At this rate, we won’t have any time left to put the wreaths up in the dining hall!”

“If you can optimize the work the forklifts are doing, maybe they would have time to spare to break through the wall.”

“Some kind of electrical surge seems to have fried them. I’ll try to get them online soon.”

Welcome to the North Pole! Your job is to find all of the invalid IDs that appear in the given ranges.

“Due to new security protocols, the password is locked in the safe below. Please see the attached document for the new combination.”