use std::collections::HashSet;

pub fn parse_rucksacks(input: &String) -> Vec<(HashSet<char>, HashSet<char>)> {
    let lines = input.lines();
    let mut rucksacks = Vec::new();

    for line in lines {
        let length = line.len();
        assert!(length % 2 == 0);
        let (first, second) = line.split_at(length / 2);
        rucksacks.push((first.chars().collect(), second.chars().collect()));
    }

    rucksacks
}

pub fn priority(c: char) -> u32 {
    assert!(c.is_ascii_alphabetic());
    let ord = c as u32;
    if c.is_ascii_lowercase() {
        1 + ord - 'a' as u32
    } else {
        27 + ord - 'A' as u32
    }
}