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use std::str::FromStr;
use anyhow::{anyhow, Result};
use crate::{Problem, Solution};
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
struct Game {
shapes: (Shape, Shape),
outcome: Outcome,
score: usize,
}
impl Game {
fn new(a: Shape, b: Shape, outcome: Outcome) -> Self {
Self {
shapes: (a, b),
outcome,
score: b as usize + outcome as usize,
}
}
}
impl From<(Shape, Shape)> for Game {
fn from((a, b): (Shape, Shape)) -> Self {
Self::new(a, b, (a, b).into())
}
}
impl From<(Shape, Outcome)> for Game {
fn from((a, outcome): (Shape, Outcome)) -> Self {
Self::new(a, (a, outcome).into(), outcome)
}
}
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[repr(u8)]
enum Outcome {
Loss = 0,
Draw = 3,
Win = 6,
}
impl From<(Shape, Shape)> for Outcome {
fn from((a, b): (Shape, Shape)) -> Self {
match (a, b) {
(Shape::Rock, Shape::Rock) => Outcome::Draw,
(Shape::Rock, Shape::Paper) => Outcome::Win,
(Shape::Rock, Shape::Scissors) => Outcome::Loss,
(Shape::Paper, Shape::Rock) => Outcome::Loss,
(Shape::Paper, Shape::Paper) => Outcome::Draw,
(Shape::Paper, Shape::Scissors) => Outcome::Win,
(Shape::Scissors, Shape::Rock) => Outcome::Win,
(Shape::Scissors, Shape::Paper) => Outcome::Loss,
(Shape::Scissors, Shape::Scissors) => Outcome::Draw,
}
}
}
impl FromStr for Outcome {
type Err = anyhow::Error;
fn from_str(s: &str) -> Result<Self, Self::Err> {
match s {
"X" => Ok(Outcome::Loss),
"Y" => Ok(Outcome::Draw),
"Z" => Ok(Outcome::Win),
s => Err(anyhow!("Unknown symbol: {}", s)),
}
}
}
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
enum Shape {
Rock = 1,
Paper = 2,
Scissors = 3,
}
impl From<(Shape, Outcome)> for Shape {
fn from((shape, outcome): (Shape, Outcome)) -> Self {
match (shape, outcome) {
(Shape::Rock, Outcome::Draw) => Shape::Rock,
(Shape::Rock, Outcome::Win) => Shape::Paper,
(Shape::Rock, Outcome::Loss) => Shape::Scissors,
(Shape::Paper, Outcome::Loss) => Shape::Rock,
(Shape::Paper, Outcome::Draw) => Shape::Paper,
(Shape::Paper, Outcome::Win) => Shape::Scissors,
(Shape::Scissors, Outcome::Win) => Shape::Rock,
(Shape::Scissors, Outcome::Loss) => Shape::Paper,
(Shape::Scissors, Outcome::Draw) => Shape::Scissors,
}
}
}
impl FromStr for Shape {
type Err = anyhow::Error;
fn from_str(s: &str) -> Result<Self, Self::Err> {
match s {
"A" | "X" => Ok(Shape::Rock),
"B" | "Y" => Ok(Shape::Paper),
"C" | "Z" => Ok(Shape::Scissors),
s => Err(anyhow!("Unknown symbol: {}", s)),
}
}
}
pub struct Day02;
impl Problem for Day02 {
const DAY: u8 = 3;
const INPUT: &'static str = include_str!("../input/day_2.txt");
}
impl Solution for Day02 {
type Answer1 = usize;
type Answer2 = usize;
fn part_1(input: &str) -> Result<Self::Answer1, anyhow::Error> {
input.lines().try_fold(0, |acc, l| {
let (a, b) = l
.split_once(' ')
.ok_or_else(|| anyhow!("Missing deliminator"))?;
let a: Shape = a.parse()?;
let b: Shape = b.parse()?;
let game: Game = (a, b).into();
Ok(acc + game.score)
})
}
fn part_2(input: &str) -> Result<Self::Answer2, anyhow::Error> {
input.lines().try_fold(0, |acc, l| {
let (a, outcome) = l
.split_once(' ')
.ok_or_else(|| anyhow!("Missing deliminator"))?;
let a: Shape = a.parse()?;
let outcome: Outcome = outcome.parse()?;
let game: Game = (a, outcome).into();
Ok(acc + game.score)
})
}
}
#[cfg(test)]
mod tests {
use super::*;
const INPUT: &str = indoc::indoc! {"
A Y
B X
C Z
"};
#[test]
fn test_part_1_example() -> Result<()> {
Ok(assert_eq!(15, Day02::part_1(INPUT)?))
}
#[test]
fn test_part_2_example() -> Result<()> {
Ok(assert_eq!(12, Day02::part_2(INPUT)?))
}
}
|
