making 2023 a generic aoc repo

2023/day-4/src/part1.rs

@@ -0,0 +1,106 @@
+#![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::*;
+
+    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());
+    }
+}