Advent of Code 2021

OvermindDL1 · 3 December 2021 23:32

I did Day 3 in this time:

Year2021 - Day3

Step 1: 3969000
Step 2: 4267809
Day3 Time Taken: 161.628µs

It was oddly fun to optimize, I did the oxygen/co2 lookup without allocating anything, using a kind of quicksort to subdivide the regions of bits and ignoring the bits I didn’t care about until I had the final top and bottom sorted to single values and those were my co2 and oxygen values, was fun. ^.^

It’s on github with the rest of course:

github.com

OvermindDL1/advent_of_code/blob/trunk/src/aoc/year2021/day3.rs

use crate::aoc::helpers::*;
use crate::AocApp;
use anyhow::Context;
use clap::Parser;
use itertools::Itertools;
use std::cmp::Ordering;
use std::path::PathBuf;

#[derive(Debug, Parser)]
pub struct Day3 {
	/// The input file of "diagnostic bits"
	#[clap(default_value = "inputs/2021/day3.input")]
	pub input_file: PathBuf,
	/// The bitcount per line cache size
	#[clap(long, short, default_value = "12")]
	pub bitcount_cache_size: usize,
}

impl Day3 {
	pub fn run(&self, _app: &AocApp) -> anyhow::Result<()> {

This file has been truncated. show original

One part I initially screwed up on was when I put println!("Step 2: {}", oxygen_rating & co2_rating); instead of println!("Step 2: {}", oxygen_rating * co2_rating);, lol…