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#![allow(dead_code)]
#![allow(unused_variables)]
use crate::prelude::*;
pub fn parse(
fh: File,
) -> Result<impl Iterator<Item = (HashSet<char>, HashSet<char>)>> {
Ok(parse::lines(fh).map(|line| {
let (first, second) = line.split_at(line.len() / 2);
let first: HashSet<char> = first.chars().collect();
let second: HashSet<char> = second.chars().collect();
(first, second)
}))
}
pub fn part1(
sacks: impl Iterator<Item = (HashSet<char>, HashSet<char>)>,
) -> Result<i64> {
Ok(sacks
.map(|(first, second)| {
i64::from(priority(*first.intersection(&second).next().unwrap()))
})
.sum())
}
pub fn part2(
mut sacks: impl Iterator<Item = (HashSet<char>, HashSet<char>)>,
) -> Result<i64> {
let mut total = 0;
while let (Some(first), Some(second), Some(third)) =
(sacks.next(), sacks.next(), sacks.next())
{
let first: HashSet<char> = first.0.union(&first.1).copied().collect();
let second: HashSet<char> =
second.0.union(&second.1).copied().collect();
let third: HashSet<char> = third.0.union(&third.1).copied().collect();
total += i64::from(priority(
*(&(&first & &second) & &third).iter().next().unwrap(),
));
}
Ok(total)
}
fn priority(c: char) -> u32 {
match c {
'a'..='z' => u32::from(c) - u32::from('a') + 1,
'A'..='Z' => u32::from(c) - u32::from('A') + 27,
_ => unreachable!(),
}
}
#[test]
fn test() {
assert_eq!(
part1(parse(parse::data(2022, 3).unwrap()).unwrap()).unwrap(),
8493
);
assert_eq!(
part2(parse(parse::data(2022, 3).unwrap()).unwrap()).unwrap(),
2552
);
}
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