pub fn p1(input: &str) -> String {
    let mut left: Vec<u32> = vec![];
    let mut right: Vec<u32> = vec![];
    for line in input.lines() {
        let mut fields = line.split_whitespace();
        let e = "Wrong file format";
        left.push(fields.next().expect(e).parse().expect(e));
        right.push(fields.next().expect(e).parse().expect(e));
    }
    left.sort_unstable();
    right.sort_unstable();

    let mut distance: u32 = 0;
    for i in 0..left.len() {
        let l = left[i];
        let r = right[i];
        distance += if l >= r { l - r } else { r - l };
    }

    distance.to_string()
}

use std::collections::HashMap;

pub fn p2(input: &str) -> String {
    let mut left: Vec<u32> = vec![];
    let mut right: HashMap<u32, u32> = HashMap::new();
    for line in input.lines() {
        let mut fields = line.split_whitespace();
        let e = "Wrong file format";
        left.push(fields.next().expect(e).parse().expect(e));
        let r: u32 = fields.next().expect(e).parse().expect(e);
        match right.get(&r) {
            None => right.insert(r, 1),
            Some(v) => right.insert(r, v + 1),
        };
    }

    let mut distance: u32 = 0;
    for l in left {
        distance += l * right.get(&l).unwrap_or(&0);
    }

    distance.to_string()
}