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
|
use std::collections::HashSet;
static DAY: u8 = 6;
fn main() {
let input = advent::read_file(DAY);
println!("{DAY}a: {}", start_of_packet(&input));
println!("{DAY}b: {}", start_of_message(&input));
}
fn start_of_prefix(input: &str, prefix_len: usize) -> usize {
input.trim()
.chars()
.collect::<Vec<_>>()
.windows(prefix_len)
.enumerate()
.map(|(pos, window)| (pos + prefix_len, window.iter().collect::<HashSet<_>>()))
.find(|(_, set)| set.len() == prefix_len)
.unwrap_or_else(|| panic!("set should contain {} different characters", prefix_len))
.0
}
fn start_of_packet(input: &str) -> usize {
start_of_prefix(input, 4)
}
fn start_of_message(input: &str) -> usize {
start_of_prefix(input, 14)
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test() {
assert_eq!(start_of_packet("mjqjpqmgbljsphdztnvjfqwrcgsmlb"), 7);
assert_eq!(start_of_packet("bvwbjplbgvbhsrlpgdmjqwftvncz"), 5);
assert_eq!(start_of_packet("nppdvjthqldpwncqszvftbrmjlhg"), 6);
assert_eq!(start_of_packet("nznrnfrfntjfmvfwmzdfjlvtqnbhcprsg"), 10);
assert_eq!(start_of_packet("zcfzfwzzqfrljwzlrfnpqdbhtmscgvjw"), 11);
assert_eq!(start_of_message("mjqjpqmgbljsphdztnvjfqwrcgsmlb"), 19);
assert_eq!(start_of_message("bvwbjplbgvbhsrlpgdmjqwftvncz"), 23);
assert_eq!(start_of_message("nppdvjthqldpwncqszvftbrmjlhg"), 23);
assert_eq!(start_of_message("nznrnfrfntjfmvfwmzdfjlvtqnbhcprsg"), 29);
assert_eq!(start_of_message("zcfzfwzzqfrljwzlrfnpqdbhtmscgvjw"), 26);
}
}
|
