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use std::fs;
use std::io::{self, BufRead};
fn badge_find(items: &[u8]) -> u64 {
items
.iter()
.fold(0, |badge, &item| badge | 1 << (item - 64))
}
fn repetition_find(items: &[u8]) -> u32 {
let len = items.len() / 2;
let left_pack = &items[..len];
let right_pack = &items[len..];
let (mut left, mut right) = (0u64, 0u64);
let mut total = 0;
for i in 0..len {
left |= 1 << left_pack[i] - 64;
right |= 1 << right_pack[i] - 64;
let cross = left & right;
if cross > 0 {
total += priority(cross);
break;
}
}
total
}
fn priority(item: u64) -> u32 {
let item = item.trailing_zeros();
if item < 32 {
item + 26
} else {
item - 32
}
}
fn solve_prio() -> u32 {
let file = fs::File::open("input").unwrap();
let lines = io::BufReader::new(file).lines();
let mut total = 0;
for line in lines {
total += repetition_find(line.unwrap().as_bytes());
}
total
}
fn solve_badge() -> u32 {
let file = fs::File::open("input").unwrap();
let lines = io::BufReader::new(file).lines();
let mut total = 0;
let mut badge = u64::MAX;
let mut grouper = 0;
for line in lines {
let items = line.unwrap();
badge &= badge_find(items.as_bytes());
grouper += 1;
if grouper % 3 == 0 {
total += priority(badge);
badge = u64::MAX;
}
}
total
}
fn main() {
assert_eq!(8072, solve_prio());
assert_eq!(2567, solve_badge());
println!("All test passed.")
}
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