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path: root/src/bin/day2.rs
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fn main() {
    let input = advent::read_lines(2);
    println!("2a: {}", calculate(&input, area_with_slack));
    println!("2b: {}", calculate(&input, ribbon_length));
}

fn area_with_slack(a: u32, b: u32, c: u32) -> u32 {
    let x = a * b;
    let y = a * c;
    let z = b * c;
    let slack = *[x, y, z].iter().min().unwrap();
    2*x + 2*y + 2*z + slack
}

fn ribbon_length(a: u32, b: u32, c: u32) -> u32 {
    let mut lens = Vec::from([a, b, c]);
    lens.sort();

    2 * lens[0] + 2 * lens[1] + lens.iter().product::<u32>()
}

fn calculate<T: AsRef<str>>(input: &[T], f: fn(u32, u32, u32) -> u32) -> u32 {
    input.iter()
         .map(|line| line.as_ref()
                         .splitn(3, 'x')
                         .map(|n| n.parse::<u32>().unwrap())
                         .collect::<Vec<u32>>())
         .map(|v| f(v[0], v[1], v[2]))
         .sum()
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_area() {
        assert_eq!(area_with_slack(2,3,4), 58);
        assert_eq!(area_with_slack(1,1,10), 43);
    }

    #[test]
    fn test_ribbon() {
        assert_eq!(ribbon_length(2,3,4), 34);
        assert_eq!(ribbon_length(1,1,10), 14);
    }
}