Files
AOC/2023/day-4/src/part1.rs
2023-12-06 22:18:41 -05:00

122 lines
3.3 KiB
Rust

#![warn(clippy::all, clippy::pedantic)]
use nom::{
bytes::complete::tag,
character::complete,
multi::{fold_many1, separated_list1},
sequence::{preceded, separated_pair, tuple},
IResult,
};
use std::collections::HashSet;
struct Card {
pub _id: u8,
pub game_numbers: HashSet<u8>,
pub my_numbers: HashSet<u8>,
}
impl Card {
fn get_win_count(&self) -> usize {
self.my_numbers.intersection(&self.game_numbers).count()
}
fn get_score(&self) -> Option<usize> {
let count = self.get_win_count();
if count == 0 {
None
} else {
Some(2_usize.pow(u32::try_from(count).expect("shouldn't have a lot of cards") - 1))
}
}
}
/// day 4 part 1 of aoc 2023
///
/// # Arguments
/// - input the input for today's puzzle
///
/// # Panics
/// panics whne it cannot parse the input OR when ever the number of game numbers is greater than
/// usize
#[must_use]
pub fn part1(input: &str) -> String {
let (_, cards) = parse_input(input).expect("there should be input");
cards
.iter()
.filter_map(Card::get_score)
.sum::<usize>()
.to_string()
}
fn parse_num_list(input: &str) -> IResult<&str, HashSet<u8>> {
fold_many1(
tuple((complete::u8, complete::space0)),
HashSet::new,
|mut acc, (x, _)| {
acc.insert(x);
acc
},
)(input)
}
fn parse_numbers(input: &str) -> IResult<&str, (HashSet<u8>, HashSet<u8>)> {
separated_pair(
parse_num_list,
tuple((tag("|"), complete::space1)),
parse_num_list,
)(input)
}
fn parse_card(input: &str) -> IResult<&str, Card> {
let (input, (id, (my_numbers, game_numbers))) = separated_pair(
preceded(tuple((tag("Card"), complete::space1)), complete::u8),
tuple((tag(":"), complete::space1)),
parse_numbers,
)(input)?;
Ok((
input,
Card {
_id: id,
game_numbers,
my_numbers,
},
))
}
fn parse_input(input: &str) -> IResult<&str, Vec<Card>> {
separated_list1(complete::line_ending, parse_card)(input)
}
#[cfg(test)]
mod test {
use super::*;
use rstest::rstest;
#[rstest]
#[case("Card 1: 41 48 83 86 17 | 83 86 6 31 17 9 48 53", Some(8))]
#[case("Card 2: 13 32 20 16 61 | 61 30 68 82 17 32 24 19", Some(2))]
#[case("Card 3: 1 21 53 59 44 | 69 82 63 72 16 21 14 1", Some(2))]
#[case("Card 4: 41 92 73 84 69 | 59 84 76 51 58 5 54 83", Some(1))]
#[case("Card 5: 87 83 26 28 32 | 88 30 70 12 93 22 82 36", None)]
#[case("Card 6: 31 18 13 56 72 | 74 77 10 23 35 67 36 11", None)]
fn line_test(#[case] line: &str, #[case] expected: Option<usize>) {
let (input, card) = parse_card(line).expect("card should be parsed");
assert_eq!(input, "");
assert_eq!(card.get_score(), expected);
}
const INPUT: &str = "Card 1: 41 48 83 86 17 | 83 86 6 31 17 9 48 53
Card 2: 13 32 20 16 61 | 61 30 68 82 17 32 24 19
Card 3: 1 21 53 59 44 | 69 82 63 72 16 21 14 1
Card 4: 41 92 73 84 69 | 59 84 76 51 58 5 54 83
Card 5: 87 83 26 28 32 | 88 30 70 12 93 22 82 36
Card 6: 31 18 13 56 72 | 74 77 10 23 35 67 36 11";
#[test]
fn part1_works() {
let result = part1(INPUT);
assert_eq!(result, "13".to_string());
}
}