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use std::str::FromStr;
use crate::{Problem, Solution};
pub struct Day02;
impl Problem for Day02 {
const DAY: u8 = 2;
const INPUT: &'static str = include_str!("../input/day_02.txt");
}
impl Solution for Day02 {
type Answer1 = usize;
type Answer2 = usize;
fn part_1(input: &str) -> anyhow::Result<Self::Answer1> {
// only 12 red cubes, 13 green cubes, and 14 blue cubes
const MAX_SET: CubeSet = CubeSet {
red: 12,
green: 13,
blue: 14,
};
Ok(input
.trim()
.split('\n')
.map(Game::from_str)
.try_collect::<Vec<_>>()?
.iter()
.filter_map(|s| s.is_valid(&MAX_SET).then_some(s.id))
.sum())
}
fn part_2(input: &str) -> anyhow::Result<Self::Answer2> {
Ok(input
.trim()
.split('\n')
.map(Game::from_str)
.try_collect::<Vec<_>>()?
.into_iter()
.map(Game::min_set)
.try_collect::<Vec<_>>()?
.iter()
.map(CubeSet::power)
.sum())
}
}
#[derive(Debug, Default)]
struct Game {
id: usize,
sets: Vec<CubeSet>,
}
impl Game {
fn is_valid(&self, max_set: &CubeSet) -> bool {
self.sets.iter().all(|c| c.is_valid(max_set))
}
fn min_set(self) -> Result<CubeSet, anyhow::Error> {
self.sets
.into_iter()
.reduce(|acc, c| c.maximize(acc))
.ok_or(anyhow::format_err!("No sets found in game"))
}
}
impl FromStr for Game {
type Err = anyhow::Error;
fn from_str(s: &str) -> Result<Self, Self::Err> {
let (id, round) = s
.trim()
.split_once(':')
.ok_or(anyhow::format_err!("Invalid game format"))?;
let id = id
.strip_prefix("Game ")
.ok_or(anyhow::format_err!("Invalid game format"))?
.parse()?;
let round = round
.trim()
.split(';')
.map(CubeSet::from_str)
.collect::<Result<_, _>>()?;
Ok(Game { id, sets: round })
}
}
#[derive(Debug, Default)]
struct CubeSet {
red: u16,
green: u16,
blue: u16,
}
impl CubeSet {
fn is_valid(&self, CubeSet { red, green, blue }: &CubeSet) -> bool {
&self.red <= red && &self.green <= green && &self.blue <= blue
}
fn maximize(&self, CubeSet { red, green, blue }: CubeSet) -> CubeSet {
CubeSet {
red: self.red.max(red),
green: self.green.max(green),
blue: self.blue.max(blue),
}
}
fn power(&self) -> usize {
(self.red * self.green * self.blue) as usize
}
}
impl FromStr for CubeSet {
type Err = anyhow::Error;
fn from_str(s: &str) -> Result<Self, Self::Err> {
s.trim().split(',').try_fold(Self::default(), |mut acc, s| {
let (n, c) = s
.trim()
.split_once(' ')
.ok_or(anyhow::format_err!("Invalid cube format: {s}"))?;
let n = u16::from_str(n)?;
match c {
"red" => acc.red += n,
"green" => acc.green += n,
"blue" => acc.blue += n,
_ => anyhow::bail!("Invalid cube color"),
};
Ok(acc)
})
}
}
#[cfg(test)]
mod tests {
use super::*;
const INPUT: &str = indoc::indoc! {"
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
"};
#[test]
fn test_part_1() -> anyhow::Result<()> {
Ok(assert_eq!(8, Day02::part_1(INPUT)?))
}
#[test]
fn test_part_2() -> anyhow::Result<()> {
Ok(assert_eq!(2286, Day02::part_2(INPUT)?))
}
}
|
