Advent of Code 2025

“After bumping around for a few minutes, you emerge into a large, well-lit cavern full of Christmas trees!”

“It’s a good thing you’re here! We just installed a new server rack, but we aren’t having any luck getting the reactor to communicate with it!”

“The Elves do have the manual for the machines, but the section detailing the initialization procedure was eaten by a Shiba Inu.”

“You slide down the firepole in the corner of the playground and land in the North Pole base movie theater!”

“The Elves were right; they definitely don’t have enough extension cables.”

“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.”