• Table of Contents
• Github

1
2

#lang iracket/lang #:require racket
(require "../advent.rkt" threading)

Day 3 - Part 1

Rucksack Reorganization

We’re given some sample input:

vJrwpWtwJgWrhcsFMMfFFhFp
jqHRNqRjqzjGDLGLrsFMfFZSrLrFZsSL
PmmdzqPrVvPwwTWBwg
wMqvLMZHhHMvwLHjbvcjnnSBnvTQFn
ttgJtRGJQctTZtZT
CrZsJsPPZsGzwwsLwLmpwMDw

The first half of each list contains items for one compartment of the backpack, and the second half contains items for the other compartment. Each backpack has, erroneously, one item in both compartments/halves.

Lower case items have priorities 1 to 26; upper case items 27 to 52.

Find the item type that appears in both compartments of each rucksack. What is the sum of the priorities of those item types?

• Table of Contents
• Github

1
2

#lang iracket/lang #:require racket
(require "../advent.rkt")

Day 2 - Part 1

Rock, Paper, Scissors

For example, suppose you were given the following strategy guide:

A Y
B X
C Z

We’re told that A=Rock, B=Paper and C=Scissors, and it’s proposed that X=Rock, Y=Paper and Z=Scissors.

We’re also told the score is computed as follows: add the score of the shape (1 for Rock, 2 for Paper and 3 for Scissors) to the outcome (0 if we lost, 3 if a draw and 6 if we won).

What would your total score be if everything goes exactly according to your strategy guide?

• Table of Contents
• Github

Each day will have some preliminary setup code:

1
2
3

#lang iracket/lang #:require racket
(require "../advent.rkt")
(require threading)

Day 1 - Part 1

We’re given the following sample data:

1000
2000
3000

4000

5000
6000

7000
8000
9000

10000

This list represents the Calories of the food carried by five Elves:

• The first Elf is carrying food with 1000, 2000, and 3000 Calories, a total of 6000 Calories.
• The second Elf is carrying one food item with 4000 Calories.
• The third Elf is carrying food with 5000 and 6000 Calories, a total of 11000 Calories.
• The fourth Elf is carrying food with 7000, 8000, and 9000 Calories, a total of 24000 Calories.
• The fifth Elf is carrying one food item with 10000 Calories.

Find the Elf carrying the most Calories. How many total Calories is that Elf carrying?

I recently started experimenting with the Racket notebook package, IRacket. Notebooks are handy for experimentation and visualization, so I wanted to be able to display a plot. I discovered that (require plot) did not work, but if I changed that slightly to (require plot/pict), I was able to display a plot in the notebook.

Table of Contents

Now that I have a couple years experience with Advent of Code, I’d like to get a little more organized prior to the contest. I’m hoping to create a blog post for most of the days, and I think I’ll make use of Ryan Culpepper’s IRacket package this year. IRacket allows creating Jupyter notebooks, and by exporting them as markdown files, they can be copy/pasted directly into a Frog static site generator file for a blog post. I thought about using only a notebook this year, but I think I would miss having a clutter-free version of just the code.

Advent of Code 2022 will start on December 1. This will be my third year, after participating in 2021 and 2020.

I hope to have time to code all of the solutions in Racket, my favorite programming language, and I should be able to translate some of them into Python and/or Javascript as a learning exercise.

My primary goal is to create an elegant Racket solution for each day’s puzzle that is clear, commented and tested. For some of the days, I may also create variants that emphasize performance or conciseness.

One of Haskell’s features I really liked was list comprehensions. I created a comparison between Haskell and Julia list comprehensions almost exactly a year ago. It appears that Python list comprehensions are as nice as either Haskell’s or Julia’s! Although, having to use Python’s lambda form to simulate the more concise Haskell/Julia function definition is less than ideal.

Advent of Code 2021 is about to start on December 1.

I recently converted a number of websites over to using Let’s Encrypt for SSL certificates, and the process was much easier than I expected.

I’ve come across the Fourier Transform a number of times, but I don’t think I ever developed a good intuition for what was going on. The following 3Blue1Brown video does a great job of providing that intuition.