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new post: SELECT solution FROM aoc WHERE year = 2022

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Jan-Erik Rediger 2022-12-09 11:21:45 +01:00
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---
permalink: "/{{ year }}/{{ month }}/{{ day }}/select-solution-from-aoc-where-year-2022"
title: "SELECT solution FROM aoc WHERE year = 2022"
published_date: "2022-12-09 11:20:00 +0100"
layout: post.liquid
data:
route: blog
---
Every year [Advent of Code][aoc] happens.
Every year I'm not super enthusiastic to actually solve those challenges.
Every year I still start (and then maybe stop after some days).
2022 was similar.
I don't have a new programming language to learn and I still write enough code day-by-day that more coding is not really necessary.
But yet sometimes it can be kind of nice to have a small challenge with a clear solution to go for
and so I set myself some rules and went ahead.
## My own rules
* Solve it in SQL.
* I started to run that in [BigQuery], but moved to [SQLite].
* Only the SQL the system provides. How far can I take this?
* It was easier on BigQuery with its large base of functionality, including string procesing, arrays, structs, ...
* On SQLite initially I tried to avoid any custom functionality, I later relaxed this rule: [SQLean] is okay occasionally.
* Once (so far) I used Python to preprocess the data. SQL is just really not good at text processing.
* Getting the solution once is good enough.
* The code can be ugly, messy and inefficient.
* I don't write tests.
* I do test. Just manually against the test input.
* No persistent data.
* It's all in-memory tables, CTEs, temporary views and a bunch of `SELECT`.
* Learn some arcane SQL features.
* Did you know SQL can recurse and select over windows? I do now!
These are my rules. I break them when I feel like it.
[AoC]: https://adventofcode.com/
[bigquery]: https://cloud.google.com/bigquery/
[sqlite]: https://sqlite.org/
[sqlean]: https://github.com/nalgeon/sqlean
## Sneak peek of day 1
`SELECT solution FROM aoc WHERE year = 2022 AND day = 1;`
I plan to release my solutions publicly, but I haven't yet.
So for now you get my solution to day 1:
```sql
CREATE TABLE data(raw);
.import input01.txt data
WITH
groups AS (
SELECT rowid, ROW_NUMBER() OVER (ORDER BY rowid) cat FROM data WHERE raw = ''
),
elves AS (
SELECT
COALESCE(
(SELECT cat FROM groups WHERE data.rowid < groups.rowid LIMIT 1),
(SELECT cat + 1 FROM groups ORDER BY cat DESC LIMIT 1)
) AS elf,
raw as calories
FROM data WHERE raw != ''
),
part1 AS (
SELECT
elf,
SUM(calories) AS total_calories
FROM elves
GROUP BY 1
ORDER BY 2 DESC
)
--SELECT * FROM part1;
SELECT SUM(total_calories) as best_3 FROM (
SELECT * FROM part1 LIMIT 3
);
```
Runnable as:
```
sqlite3 < aoc01.sql
```
(Oh, another rule: It needs to run as `sqlite3 < script.sql`)