From 02e78aea8f529ff80d7b5d12e567ba609341ea26 Mon Sep 17 00:00:00 2001
From: Daniel Flanagan <daniel@lyte.dev>
Date: Sat, 9 Dec 2023 10:52:38 -0600
Subject: [PATCH] Day 4 part 1

---
 2023/rust/src/day4.rs | 83 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 83 insertions(+)
 create mode 100644 2023/rust/src/day4.rs

diff --git a/2023/rust/src/day4.rs b/2023/rust/src/day4.rs
new file mode 100644
index 0000000..0444667
--- /dev/null
+++ b/2023/rust/src/day4.rs
@@ -0,0 +1,83 @@
+mod prelude;
+extern crate nom;
+use nom::{
+    branch::alt,
+    bytes::complete::{tag, take_while},
+    character::complete::space1,
+    combinator::{map_res, value},
+    multi::separated_list0,
+    sequence::tuple,
+    IResult,
+};
+use std::{collections::HashSet, iter::FromIterator};
+
+use crate::prelude::*;
+
+fn main() {
+    Day4::show(day_input(4), day_input(4))
+}
+
+#[derive(Debug)]
+struct Card {
+    id: usize,
+    winning: HashSet<usize>,
+    has: Vec<usize>,
+}
+
+impl Card {
+    fn points(&self) -> usize {
+        let num_winning = self.has.iter().filter(|n| self.winning.contains(n)).count() as u32;
+        println!("{self:?} num_winning -> {num_winning}");
+        if num_winning >= 1 {
+            2_u64.pow(num_winning - 1) as usize
+        } else {
+            0
+        }
+    }
+}
+
+// parser
+fn int(input: &str) -> IResult<&str, usize> {
+    map_res(take_while(char::is_numeric), str::parse)(input)
+}
+
+fn card(input: &str) -> IResult<&str, Card> {
+    let (input, id) = int(tuple((tag("Card"), space1))(input)?.0)?;
+    let (input, winning_list) = separated_list0(space1, int)(tuple((tag(":"), space1))(input)?.0)?;
+    let (input, has) = separated_list0(space1, int)(tuple((space1, tag("|"), space1))(input)?.0)?;
+    let winning = HashSet::from_iter(winning_list);
+    Ok((input, Card { id, winning, has }))
+}
+
+struct Day4 {}
+impl Day4 {}
+impl AoCSolution for Day4 {
+    type Input = String;
+    type Solution = usize;
+
+    fn part1(input: Self::Input) -> Self::Solution {
+        input.lines().map(|s| card(s).unwrap().1.points()).sum()
+    }
+
+    fn part2(input: Self::Input) -> Self::Solution {
+        0
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test() {
+        let input = r#"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"#;
+        println!("input:\n{input}");
+        assert_eq!(Day4::part1(input.into()), 13);
+        assert_eq!(Day4::part2(input.into()), 0);
+    }
+}