day03.rs

use crate::solutions::Solution;
use regex::Regex;

pub struct Day03;

impl Solution for Day03 {
    fn part_one(&self, input: &str) -> String {
        let re = Regex::new(r"mul\((\d{1,3}),(\d{1,3})\)").unwrap();

        re.captures_iter(input)
            .map(|capture| {
                let left = capture[1].parse::<usize>().unwrap();
                let right = capture[2].parse::<usize>().unwrap();

                left * right
            })
            .sum::<usize>()
            .to_string()
    }

    fn part_two(&self, input: &str) -> String {
        let re = Regex::new(r"do\(\)|don't\(\)|mul\((\d{1,3}),(\d{1,3})\)").unwrap();
        let mut enabled: bool = true;

        re.captures_iter(input)
            .filter_map(|capture| {
                let case = capture.get(0).unwrap().as_str();

                match case {
                    "do()" => enabled = true,
                    "don't()" => enabled = false,
                    _ if enabled => {
                        let left = capture[1].parse::<usize>().unwrap();
                        let right = capture[2].parse::<usize>().unwrap();

                        return Some(left * right);
                    }
                    _ => (),
                }

                None
            })
            .sum::<usize>()
            .to_string()
    }
}

#[cfg(test)]
mod tests {
    use crate::solutions::year2024::day03::Day03;
    use crate::solutions::Solution;

    const EXAMPLE: &str =
        r#"xmul(2,4)%&mul[3,7]!@^do_not_mul(5,5)+mul(32,64]then(mul(11,8)mul(8,5))"#;
    const EXAMPLE_TWO: &str =
        r#"xmul(2,4)&mul[3,7]!^don't()_mul(5,5)+mul(32,64](mul(11,8)undo()?mul(8,5))"#;

    const MULTILINE_EXAMPLE: &str = r#"don't()mul(4,2)
    mul(3,5)
    do()mul(2,2)
    "#;

    #[test]
    fn part_one_example_test() {
        assert_eq!("161", Day03.part_one(EXAMPLE));
    }

    #[test]
    fn part_two_example_test() {
        assert_eq!("48", Day03.part_two(EXAMPLE_TWO));
    }

    #[test]
    fn part_two_my_examples() {
        assert_eq!("191274", Day03.part_two("?)do())mul(449,426)"));
        assert_eq!("0", Day03.part_two("?)do())don't()mul(2,3)"));
        assert_eq!("0", Day03.part_two("?)do())don't()3{}mul(2,3)"));
        assert_eq!("20", Day03.part_two("?)do()don't()do()mul(5,4)"));
        assert_eq!("24", Day03.part_two("?)do()mul(2,2)don't()do()mul(5,4)"));
        assert_eq!(
            "24",
            Day03.part_two("?)do()mul(2,2)don't()mul(3,2)do()mul(5,4)")
        );
        assert_eq!("20", Day03.part_two("?)mul(5,4)"));
        assert_eq!("4", Day03.part_two(MULTILINE_EXAMPLE));
    }
}