drgeraint, 6 months ago

I just completed "Cube Conundrum" - Day 2 - Advent of Code 2023 #AdventOfCode https://adventofcode.com/2023/day/2

https://github.com/drgeraint/adventofcode2023/tree/main/day02

drgeraint, 6 months ago

I just completed "Gear Ratios" - Day 3 - Advent of Code 2023 #AdventOfCode https://adventofcode.com/2023/day/3

https://github.com/drgeraint/adventofcode2023/tree/main/day03

drgeraint, 6 months ago

I just completed "Scratchcards" - Day 4 - Advent of Code 2023 #AdventOfCode https://adventofcode.com/2023/day/4

https://github.com/drgeraint/adventofcode2023/tree/main/day04

drgeraint, 6 months ago

I just completed "If You Give A Seed A Fertilizer" - Day 5 - Advent of Code 2023 #AdventOfCode https://adventofcode.com/2023/day/5

https://github.com/drgeraint/adventofcode2023/tree/main/day05

drgeraint, 6 months ago

I just completed "Wait For It" - Day 6 - Advent of Code 2023 #AdventOfCode https://adventofcode.com/2023/day/6

https://github.com/drgeraint/adventofcode2023/tree/main/day06

drgeraint, 6 months ago

I just completed "Camel Cards" - Day 7 - Advent of Code 2023 #AdventOfCode https://adventofcode.com/2023/day/7

https://github.com/drgeraint/adventofcode2023/tree/main/day07

drgeraint, 6 months ago

I just completed "Haunted Wasteland" - Day 8 - Advent of Code 2023 #AdventOfCode https://adventofcode.com/2023/day/8

https://github.com/drgeraint/adventofcode2023/tree/main/day08

18+ drgeraint, 6 months ago

Meh, I didn't enjoy that one as much as the others so far this year.

The efficient solution depends on properties of the input data (which are not hinted in the specification) so it is not a general solution.

Also, lcm.reduce in numpy seems to give different results each time the code is run; no idea why, but I had to use Octave for the final step.

18+ jeff, 6 months ago

@drgeraint I was just happy I noticed the lcm/primes trick right away this time (from past years).

I assume everyone's inputs have intervals that are multiples of primes, with prime length instructions.

In your code, divide your intervals by your path length. LCM those, then multiply by path length. Avoids overflow.

I had to write a quick wrapper for LCM on more than 2 ints in PHP.

let $lcm = first number

foreach(subsequent number $n) $lcm = lcm($lcm, $n)