advent-of-code-2023/day-02/src/bin/part1.rs

83 lines
2.0 KiB
Rust

use nom::{
branch::alt,
bytes::complete::tag,
character::complete::{char, digit1},
combinator::{map, value},
multi::separated_list1,
sequence::{delimited, pair, terminated, tuple},
IResult,
};
fn main() {
println!("{}", part1(include_str!("./input.txt")));
}
fn part1(input: &str) -> u32 {
input.lines().map(game).sum()
}
fn game(input: &str) -> u32 {
let (id, possible) = tuple((id, all_results))(input).unwrap().1;
if possible {
id
} else {
0
}
}
fn digit_u32(i: &str) -> IResult<&str, u32> {
map(digit1, |d: &str| d.parse().unwrap())(i)
}
fn id(i: &str) -> IResult<&str, u32> {
delimited(tag("Game "), digit_u32, tag(": "))(i)
}
fn all_results(i: &str) -> IResult<&str, bool> {
map(separated_list1(tag("; "), one_result), |res| {
res.iter().all(|x| *x)
})(i)
}
fn one_result(i: &str) -> IResult<&str, bool> {
map(separated_list1(tag(", "), color), |res| {
res.iter().all(|x| *x)
})(i)
}
#[derive(Debug, PartialEq, Clone, Copy)]
enum Color {
Red,
Green,
Blue,
}
fn color(i: &str) -> IResult<&str, bool> {
map(
pair(
terminated(digit_u32, char(' ')),
alt((
value(Color::Red, tag("red")),
value(Color::Green, tag("green")),
value(Color::Blue, tag("blue")),
)),
),
|(amount, color)| match color {
Color::Red => amount <= 12,
Color::Green => amount <= 13,
Color::Blue => amount <= 14,
},
)(i)
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_part1() {
assert_eq!(part1("Game 1: 3 blue, 4 red; 1 red, 2 green, 6 blue; 2 green\nGame 2: 1 blue, 2 green; 3 green, 4 blue, 1 red; 1 green, 1 blue\nGame 3: 8 green, 6 blue, 20 red; 5 blue, 4 red, 13 green; 5 green, 1 red\nGame 4: 1 green, 3 red, 6 blue; 3 green, 6 red; 3 green, 15 blue, 14 red\nGame 5: 6 red, 1 blue, 3 green; 2 blue, 1 red, 2 green"), 8)
}
}