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#lang iracket/lang #:require racket
(require "../advent.rkt")
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I always enjoy recursive list processing in Racket :) Here’s our input today:
Card 1: 41 48 83 86 17 | 83 86 6 31 17 9 48 53
Card 2: 13 32 20 16 61 | 61 30 68 82 17 32 24 19
Card 3: 1 21 53 59 44 | 69 82 63 72 16 21 14 1
Card 4: 41 92 73 84 69 | 59 84 76 51 58 5 54 83
Card 5: 87 83 26 28 32 | 88 30 70 12 93 22 82 36
Card 6: 31 18 13 56 72 | 74 77 10 23 35 67 36 11
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#lang iracket/lang #:require racket
(require "../advent.rkt" threading)
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Day 3 involves some two dimensional analysis, so we’ll use complex numbers as a convenient two dimensional index:
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#lang iracket/lang #:require racket
(require "../advent.rkt" threading)
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Our data today is as follows:
Game 1: 3 blue, 4 red; 1 red, 2 green, 6 blue; 2 green
Game 2: 1 blue, 2 green; 3 green, 4 blue, 1 red; 1 green, 1 blue
Game 3: 8 green, 6 blue, 20 red; 5 blue, 4 red, 13 green; 5 green, 1 red
Game 4: 1 green, 3 red, 6 blue; 3 green, 6 red; 3 green, 15 blue, 14 red
Game 5: 6 red, 1 blue, 3 green; 2 blue, 1 red, 2 green
For today’s task, I found it helpful to make use of the parallel-combine combinator from Hanson & Sussman’s “Software Design for Flexibility”. This combinator applies f and g to the input, in parallel, and combines their output using h. Pictorially, it looks like this:
Day 1
For part 1, we’re given data as follows (Note: in both data examples, intraline spaces are only for emphasis):
1 abc 2
pqr 3 stu 8 vwx
a 1 b2c3d4e 5 f
treb 7 uchet
The task is to find the first and last numeric digit in each line, e.g. 1 and 2, concatenate them together, e.g. 12, and then sum all of those values.
It appears upgrading my Anaconda Python distribution killed my Emacs, so I figured I’d try upgrading to the latest version to see if that fixed things. It did :)
Since upgrading Emacs to 29.1 no longer required the manual configuration changes I had to make when upgrading to 28.2, I’ll document the procedure I used on MacOS Ventura 13.6.1
Table of Contents
My support code is unchanged, as of now, so last year’s blog post still does a good job of explaining it.
Advent of Code 2023 is starting on December 1. This will be my fourth year, after participating in 2022, 2021 and 2020.
My primary programming language is Racket, so I expect to code most of the solutions in it; however, the rest of my language stack includes Python, Javascript and C++, so I’ll code some of the solutions using them also.
I upgraded to Emacs 28.2 (MacOS Ventura), and it required a few tweaks, so I’m documenting that here for future reference.
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#lang iracket/lang #:require racket
(require "../advent.rkt")
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Tuning Trouble
Today’s puzzle has very similar parts! For both parts, our input is a single string, and the task is to determine how many characters we need to consume before finding a contiguous group of N unique characters. The only difference is the value of N.
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#lang iracket/lang #:require racket
(require "../advent.rkt")
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Supply Stacks We’re given the following sample input:
[D]
[N] [C]
[Z] [M] [P]
1 2 3
move 1 from 2 to 1
move 3 from 1 to 3
move 2 from 2 to 1
move 1 from 1 to 2
And, fortunately for us, the first part has lines padded with spaces to be of equal length - this makes parsing just a little bit easier :) Even so, the built-in parsers we have for AoC are insufficient, so we’ll just use a custom parser that reads the file into a string, splits it on "\n\n", and then maps the string-split function over both parts - the stack lines and the command lines: