1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
|
use std::collections::HashSet;
static DAY: u8 = 3;
fn main() {
let input = advent::read_lines(DAY);
println!("{DAY}a: {}", sum_priorities(&input));
println!("{DAY}b: {}", sum_badge_priorities(&input));
}
fn item_value(item: char) -> u32 {
if item.is_ascii_lowercase() {
item.to_digit(36).unwrap() - 9
} else if item.is_ascii_uppercase() {
item.to_digit(36).unwrap() + 17
} else {
panic!("unexpected common character: {}", item);
}
}
fn sum_priorities(input: &[String]) -> u32 {
let mut priorities = 0;
for line in input {
let (first, second) = line.split_at(line.len() / 2);
let first = first.chars().collect::<HashSet<_>>();
let second = second.chars().collect::<HashSet<_>>();
let common = first.intersection(&second).copied().collect::<Vec<_>>();
assert_eq!(common.len(), 1);
priorities += item_value(*common.first().unwrap());
}
priorities
}
fn sum_badge_priorities(input: &[String]) -> u32 {
let mut priorities = 0;
for group in input.chunks(3) {
let first = group[0].chars().collect::<HashSet<_>>();
let second = group[1].chars().collect::<HashSet<_>>();
let third = group[2].chars().collect::<HashSet<_>>();
let common = first.intersection(&second).copied().collect::<HashSet<_>>();
let common = common.intersection(&third).copied().collect::<Vec<_>>();
assert_eq!(common.len(), 1);
priorities += item_value(*common.first().unwrap());
}
priorities
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test() {
let input = [
"vJrwpWtwJgWrhcsFMMfFFhFp".to_string(),
"jqHRNqRjqzjGDLGLrsFMfFZSrLrFZsSL".to_string(),
"PmmdzqPrVvPwwTWBwg".to_string(),
"wMqvLMZHhHMvwLHjbvcjnnSBnvTQFn".to_string(),
"ttgJtRGJQctTZtZT".to_string(),
"CrZsJsPPZsGzwwsLwLmpwMDw".to_string(),
];
assert_eq!(sum_priorities(&input), 157);
assert_eq!(sum_badge_priorities(&input), 70);
}
}
|
