Advent of Code 2023 - Day 9
I placed 11th on part 1; 11th on part 2; still 2nd overall.
Thinking about it recursively makes this problem easy. The next number is the last number plus the next number in the difference array (recursive call), or 0 if the input is all 0 (base case).
A nice trick I didn't spot: for part 2, you can just reverse the initial sequence - the previous number of the sequence is the next number of the reverse of the sequence!
Problem: https://adventofcode.com/2023/day/9
Solution: https://github.com/jonathanpaulson/Ad...