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Here lies my solutions to Advent of Code 2020, an Advent calendar full of programming puzzles from December 1st all the way to Christmas.

This year I managed to be awake at every puzzle release (midnight EST/UTC-5, 2AM my time) and finished all them in the minutes/hours that followed! With that, I beat my last year's score, this time placing at 167th on the Global Leaderboard with 389 points across 6 leaderboard finishes! I also got top 500 on exactly half of the days, so that's cool as well! I did some pretty cools plots of my completion times over at time-plots if you want to check those out.

Inputs and Outputs

All inputs are read from inputs\inputXX.txt, with XX being the zero-padded day. As per the creator's request, they are not available in this repository and should be downloaded directly from the event website.

The only outputs for all days are exactly what should be pasted in the puzzle answer textbox, followed by the total runtime of both parts combined (via Python's time.time()), no more and no less. The only exception is when the answer is drawn on a grid-like formation, then that is printed instead of OCR. In some cases, helpful debugging code or other verbose messages are simply commented out, and can be manually toggled to better understand the code inner workings.

Implementation Goals

The solutions posted here are cleaned-up versions of the actual code written when aiming for the leaderboards. For all solutions, the main implementation goals were, in descending order:

• Readability: Clean, readable, self-explanatory and commented code above all else.
• Input Generalization: Should work not only for my input but for anyone's, with some assumptions made about it, which are noted when appropriate.
• Modularity: Avoid duplicate code where possible, allowing for easy modification by making heavy use of classes and functions.
• Speed: Use efficient algorithms, keeping runtime reasonably low without extreme micro-optimizations.
• Minimal Imports: Refrain from imports besides utilities (sys, time) and basic standard libraries (math, itertools, collections). When the knowledge of functions and structures are considered vital to the problem solution (graphs, trees, linked lists, union-find, etc.), reimplement them.

Thanks!

Many thanks to Eric Wastl, who creates Advent of Code, as well as to the amazing community over at /r/adventofcode!