day01.rs

use crate::solutions::Solution;

pub struct Day01;

impl Solution for Day01 {
    fn part_one(&self, input: &str) -> String {
        let (mut left, mut right) = self.parse(input);

        left.sort_unstable();
        right.sort_unstable();

        left.iter()
            .zip(&right)
            .map(|(a, b)| (a - b).abs())
            .sum::<i32>()
            .to_string()
    }

    fn part_two(&self, input: &str) -> String {
        let (left, right) = self.parse(input);

        left.iter()
            .map(|l| right.iter().filter(|r| *r == l).count() as i32 * l)
            .sum::<i32>()
            .to_string()
    }
}

impl Day01 {
    fn parse(&self, input: &str) -> (Vec<i32>, Vec<i32>) {
        input
            .lines()
            .map(|line| {
                let mut split = line.split_terminator("   ");
                (
                    split.next().unwrap().parse::<i32>().unwrap(),
                    split.next().unwrap().parse::<i32>().unwrap(),
                )
            })
            .unzip()
    }
}

#[cfg(test)]
mod tests {
    use crate::solutions::year2024::day01::Day01;
    use crate::solutions::Solution;

    const EXAMPLE: &str = r#"3   4
4   3
2   5
1   3
3   9
3   3"#;

    #[test]
    fn part_one_example_test() {
        assert_eq!("11", Day01.part_one(EXAMPLE));
    }

    #[test]
    fn part_two_example_test() {
        assert_eq!("31", Day01.part_two(EXAMPLE));
    }
}