static DAY: u8 = 1;

fn main() {
    let input = advent::read_lines(DAY);
    println!("{DAY}a: {}", list_distance(&input));
    println!("{DAY}b: {}", similarity(&input));
}

fn parse_numbers(numbers: &[String]) -> (Vec::<usize>, Vec::<usize>) {
    let mut list1 = Vec::new();
    let mut list2 = Vec::new();
    for pair in numbers {
        let (number1, number2) = pair.split_once("   ").unwrap();
        list1.push(number1.parse::<usize>().unwrap());
        list2.push(number2.parse::<usize>().unwrap());
    }
    (list1, list2)
}

fn list_distance(numbers: &[String]) -> usize {
    let (mut list1, mut list2) = parse_numbers(numbers);
    list1.sort();
    list2.sort();

    list1.iter()
         .enumerate()
         .map(|(i, number1)| number1.abs_diff(list2[i]))
         .sum()
}

fn similarity(numbers: &[String]) -> usize {
    let (list1, list2) = parse_numbers(numbers);

    list1.iter()
         .map(|x| x * list2.iter().filter(|&y| x == y).count())
         .sum()
}

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

    #[test]
    fn test() {
        let input = [
            "3   4",
            "4   3",
            "2   5",
            "1   3",
            "3   9",
            "3   3",
        ].iter().map(|&x| String::from(x)).collect::<Vec<_>>();
        assert_eq!(list_distance(&input), 11);
        assert_eq!(similarity(&input), 31);
    }
}