Advent of Code went from 25 days to 12 days starting this year, as it took too much time each year to come up with 25 unique challenges [1]. [1] https://advent

Advent of Code went from 25 days to 12 days starting this year, as it took too much time each year to come up with 25 unique challenges [1]. [1] https://adventofcode.com/2025/about#faq_num_days https://adventofcode.com/2025/about#faq_num_days