AOC 2024 day 03

Signed-off-by: Mårten Kongstad <[email protected]>

2024/03/Cargo.toml

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+[package]
+name = "aoc-2024-03"
+version = "0.1.0"
+authors = ["Mårten Kongstad <[email protected]>"]
+edition = "2021"
+
+[dependencies]
+anyhow = "1.0"
+aoc = { path = "../../aoc" }
+regex = "1.11.1"

2024/03/src/main.rs

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+use anyhow::Result;
+use regex::Regex;
+
+fn main() -> Result<()> {
+    let input = include_str!("input.txt");
+    aoc::run!(part_one(input), 173517243)?;
+    aoc::run!(part_two(input), 100450138)?;
+    Ok(())
+}
+
+fn parse(input: &str, support_toggle_instr: bool) -> Result<Vec<(usize, usize)>> {
+    let re = if support_toggle_instr {
+        Regex::new(r#"do\(\)|don't\(\)|mul\((\d+),(\d+)\)"#).unwrap()
+    } else {
+        Regex::new(r#"mul\((\d+),(\d+)\)"#).unwrap()
+    };
+    let mut enabled = true;
+    let mut out = vec![];
+    for caps in re.captures_iter(input) {
+        if caps[0].starts_with("mul(") {
+            if enabled {
+                let a = caps[1].parse::<usize>()?;
+                let b = caps[2].parse::<usize>()?;
+                out.push((a, b));
+            }
+        } else if caps[0] == *"don't()" {
+            enabled = false;
+        } else if caps[0] == *"do()" {
+            enabled = true;
+        };
+    }
+    Ok(out)
+}
+
+fn part_one(input: &str) -> Result<usize> {
+    let pairs = parse(input, false)?;
+    Ok(pairs.into_iter().map(|(a, b)| a * b).sum())
+}
+
+fn part_two(input: &str) -> Result<usize> {
+    let pairs = parse(input, true)?;
+    Ok(pairs.into_iter().map(|(a, b)| a * b).sum())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const INPUT_PART_ONE: &str = include_str!("test-input-part-one.txt");
+    const INPUT_PART_TWO: &str = include_str!("test-input-part-two.txt");
+
+    #[test]
+    fn test_parse() {
+        assert_eq!(
+            parse(INPUT_PART_ONE, false).unwrap(),
+            vec![(2, 4), (5, 5), (11, 8), (8, 5)]
+        );
+        assert_eq!(parse(INPUT_PART_TWO, true).unwrap(), vec![(2, 4), (8, 5)]);
+    }
+
+    #[test]
+    fn test_part_one() {
+        assert_eq!(part_one(INPUT_PART_ONE).unwrap(), 161);
+    }
+
+    #[test]
+    fn test_part_two() {
+        assert_eq!(part_two(INPUT_PART_TWO).unwrap(), 48);
+    }
+}

2024/03/src/test-input-part-one.txt

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+xmul(2,4)%&mul[3,7]!@^do_not_mul(5,5)+mul(32,64]then(mul(11,8)mul(8,5))

2024/03/src/test-input-part-two.txt

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+xmul(2,4)&mul[3,7]!^don't()_mul(5,5)+mul(32,64](mul(11,8)undo()?mul(8,5))