Add day 4

2023/day4/.gitignore

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+/target/

2023/day4/Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "day4"
+version = "0.1.0"
+dependencies = [
+ "indoc",
+ "nom",
+]
+
+[[package]]
+name = "indoc"
+version = "2.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1e186cfbae8084e513daff4240b4797e342f988cecda4fb6c939150f96315fd8"
+
+[[package]]
+name = "memchr"
+version = "2.6.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f665ee40bc4a3c5590afb1e9677db74a508659dfd71e126420da8274909a0167"
+
+[[package]]
+name = "minimal-lexical"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "68354c5c6bd36d73ff3feceb05efa59b6acb7626617f4962be322a825e61f79a"
+
+[[package]]
+name = "nom"
+version = "7.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d273983c5a657a70a3e8f2a01329822f3b8c8172b73826411a55751e404a0a4a"
+dependencies = [
+ "memchr",
+ "minimal-lexical",
+]

2023/day4/Cargo.toml

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+[package]
+name = "day4"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+indoc = "2.0.4"
+nom = "7.1.3"

2023/day4/src/main.rs

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+use std::cmp::min;
+
+use nom::{
+    bytes::complete::tag,
+    character::complete::char,
+    multi::{many1, separated_list1},
+    sequence::{preceded, separated_pair, terminated, tuple},
+};
+
+#[derive(Debug, PartialEq, Eq)]
+struct Card {
+    id: usize,
+    winning_numbers: Vec<usize>,
+    have_numbers: Vec<usize>,
+}
+
+mod parser {
+    use nom::{
+        branch::alt,
+        bytes::complete::take_while1,
+        character::complete::{char, digit1},
+        combinator::map,
+        multi::many_m_n,
+        sequence::preceded,
+        IResult,
+    };
+
+    pub fn double_digit_number(i: &str) -> IResult<&str, usize> {
+        let single_digit = preceded(char(' '), many_m_n(1, 1, digit1));
+        let double_digit = many_m_n(1, 1, digit1);
+
+        let digit = alt((single_digit, double_digit));
+
+        let mut digit = map(digit, |chars| {
+            chars
+                .into_iter()
+                .collect::<String>()
+                .parse::<usize>()
+                .unwrap()
+        });
+
+        digit(i)
+    }
+
+    pub fn number(i: &str) -> IResult<&str, usize> {
+        map(
+            take_while1::<_, &str, _>(|c| c.is_ascii_digit()),
+            |s: &str| s.parse::<usize>().unwrap(),
+        )(i)
+    }
+
+    #[cfg(test)]
+    mod tests {
+        use super::*;
+
+        #[test]
+        fn parse_double_digit() {
+            assert_eq!(double_digit_number("23").unwrap(), ("", 23));
+            assert_eq!(double_digit_number(" 3").unwrap(), ("", 3));
+            assert_eq!(double_digit_number("3 ").unwrap(), (" ", 3));
+            assert!(double_digit_number("  3").is_err());
+        }
+
+        #[test]
+        fn parse_number() {
+            assert_eq!(number("23").unwrap(), ("", 23));
+            assert_eq!(number("2").unwrap(), ("", 2));
+            assert_eq!(number("2x").unwrap(), ("x", 2));
+            assert!(number(" 3").is_err());
+        }
+    }
+}
+
+impl Card {
+    fn parse(input: &str) -> Self {
+        let card_prefix = tuple((tag("Card"), many1(char(' '))));
+
+        let winning_numbers = separated_list1(char(' '), parser::double_digit_number);
+        let have_numbers = separated_list1(char(' '), parser::double_digit_number);
+
+        let numbers = separated_pair(winning_numbers, tag(" | "), have_numbers);
+
+        let card_info = terminated(preceded(card_prefix, parser::number), char(':'));
+
+        let mut card = separated_pair(card_info, char(' '), numbers);
+
+        let (rest, (card_id, (winning_numbers, have_numbers))) = card(input).unwrap();
+
+        assert!(rest.is_empty());
+
+        Self {
+            id: card_id,
+            winning_numbers,
+            have_numbers,
+        }
+    }
+
+    fn matching_numbers(&self) -> Vec<usize> {
+        self.have_numbers
+            .iter()
+            .filter(|n| self.winning_numbers.contains(n))
+            .copied()
+            .collect()
+    }
+
+    fn value(&self) -> usize {
+        let matches = self.matching_numbers().len();
+        if matches == 0 {
+            0
+        } else {
+            2_usize.pow(matches as u32 - 1)
+        }
+    }
+}
+
+fn part1(input: &str) -> usize {
+    input
+        .lines()
+        .map(Card::parse)
+        .map(|card| card.value())
+        .sum()
+}
+
+fn part2(input: &str) -> usize {
+    let cards: Vec<Card> = input.lines().map(Card::parse).collect();
+    let mut card_count: Vec<usize> = std::iter::repeat(1).take(cards.len()).collect();
+
+    for i in 0..cards.len() {
+        let matches = cards[i].matching_numbers().len();
+        for j in (i + 1)..min(i + matches + 1, cards.len()) {
+            card_count[j] += card_count[i];
+        }
+    }
+    card_count.into_iter().sum()
+}
+
+fn main() {
+    let input = include_str!("../input");
+
+    println!("Part 1 : {}", part1(input));
+    println!("Part 2 : {}", part2(input));
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use indoc::indoc;
+
+    #[test]
+    fn example_01() {
+        let input = indoc! {"
+            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
+        "};
+
+        assert_eq!(part1(input), 13);
+    }
+
+    #[test]
+    fn parse_card() {
+        let input = "Card   1: 41 48 83  6 17 | 83 86  6 31 17  9 48 53";
+        assert_eq!(
+            Card::parse(input),
+            Card {
+                id: 1,
+                winning_numbers: vec![41, 48, 83, 6, 17],
+                have_numbers: vec![83, 86, 6, 31, 17, 9, 48, 53],
+            }
+        );
+    }
+
+    #[test]
+    fn example_02() {
+        let input = indoc! {"
+            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
+        "};
+
+        assert_eq!(part2(input), 30);
+    }
+}