# AoC 2023 Day 16: Reflectinator

## Source: Day 16: The Floor Will Be Lava

Full solution for today (spoilers!)

## Part 1

You are given a grid of mirrors (|-\/) and empty space (.).

Diagonal mirrors just relect the light.

The horizontal and vertical mirrors are splitters, light hitting them head on (like >|) will split to go both directions. Light hitting edge on will just go through it.

Starting in the top left going East, how many total tiles will a light beam illuminate?

# AoC 2023 Day 15: Hashinator

## Source: Day 15: Lens Library

Full solution for today (spoilers!)

## Part 1

Hash each input (comma separated) with h(v, c) = (v + c) * 17 (modulo 256 / as a byte). Sum these values.

# AoC 2023 Day 14: Spininator

## Source: Day 14: Parabolic Reflector Dish

Full solution for today (spoilers!)

## Part 1

Given a grid of # and O (among empty . points) where O can move, slide each O as far north as it can. Score each based on how far north it is.

# AoC 2023 Day 13: Reflectinator

## Source: Day 13: Point of Incidence

Full solution for today (spoilers!)

## Part 1

You are given a grid of . and #. Find the (single) axis of reflection (between two rows or columns).

# AoC 2023 Day 12: Question Markinator

## Source: Day 12: Hot Springs

Full solution for today (spoilers!)

## Part 1

Given a sequence of #.? as on, off, and unknown and a sequence of group sizes, determine how many possible arrangements there are that match the given groups.

More specifically, if you have ???.## 1,2 you need a single # and a set of two ##, there are three possibilities: #...###, .#..###, and ..#.###.

# AoC 2023 Day 11: Big Banginator

## Source: Day 11: Cosmic Expansion

Full solution for today (spoilers!)

## Part 1

Read a grid of # (stars) and . (empty space). For each completely empty line or row, add another. Calculate the sum of the Manhattan distances between all pairs of stars.

# AoC 2023 Day 10: Pipinator

## Source: Day 10: Pipe Maze

Full solution for today (spoilers!)

## Part 1

You are given as input an ASCII art pipe diagram with straight pipes |-, right angle turns LJ7F, ground ., and a start tile S.

The start tile will be part of a loop of pipes.

Find the distance to the furthest connected pipe segment from S (or half the length of the loop).

# AoC 2023 Day 9: Stackinator

## Source: Day 9: Mirage Maintenance

Full solution for today (spoilers!)

## Part 1

Given a list of terms, repeatedly calculate the differences of terms until these differences are 0. So:

0   3   6   9  12  15
3   3   3   3   3
0   0   0   0


Calculate the sum of next terms for each sequence (18 for this one).

# AoC 2023 Day 8: Mazinator

## Source: Day 8: Haunted Wasteland

Full solution for today (spoilers!)

## Part 1

Given a (repeated) sequence of moves (L for left and R for right) and a directed graph where each node has two neighbors (left and right), count how many total steps it takes to get from the node AAA to the node ZZZ. The sequence of moves can (and will) need to repeat.

# AoC 2023 Day 7: Pokinator

## Source: Day 7: Camel Cards

Full solution for today (spoilers!)

## Part 1

Simulate a limited poker game with no suits and break otherwise tied hands lexicographically (AAAA2 beats AKAAA) because the the hands are both four of a kind, the first cards are both A, but the second A beats the K. It doesn’t matter that the first hand’s off card was a 2

Order all hands then calculate the sum of the ordering of hands (1 for best etc) times the bet for each.