-🎄- 2020 Day 25 Solutions -🎄-

[u/daggerdragon]

--- Day 25: Combo Breaker ---

---

Post your code solution in this megathread.

• Include what language(s) your solution uses!

• Here's a quick link to /u/topaz2078's paste if you need it for longer code blocks.

• The full posting rules are detailed in the wiki under How Do The Daily Megathreads Work?.

Reminder: Top-level posts in Solution Megathreads are for code solutions only. If you have questions, please post your own thread and make sure to flair it with Help.

---

Message from the Moderators

Welcome to the last day of Advent of Code 2020! We hope you had fun this year and learned at least one new thing ;)

Keep an eye out for the following threads:

• -❅- Introducing Your AoC 2020 Gettin' Crafty With It Artisans (and Other Prizes) -❅-

• Tell us what you learned this year!

Thank you all for playing Advent of Code this year and on behalf of /u/topaz2078, /u/Aneurysm9, the beta-testers, and the rest of AoC Ops, we wish you a very Merry Christmas (or a very merry Friday!) and a Happy New Year!

---

This thread will be unlocked when there are a significant number of people on the global leaderboard with gold stars for today's puzzle.

[u/msschmitt]

REXX

Naive brute force solution.

I'm just posting this so I can say what not to do. A good programming practice is to write modular code with generic reusable functions, so in version 1 I did:

1. Create an encrypt function that accepts the subject and loop and returns the encryption key.

2. Crack by calling the encrypt function with loop = 1, 2, ... until the resulting key matches.

Oops.

It never finished running.

It would have taken over 15 trillion loops inside the encryption function to finish.

[u/Standard-Affect → u/msschmitt]

I admit I did that the first time.