38 lines
1.2 KiB
Rust
38 lines
1.2 KiB
Rust
fn find_num_chars_before_marker(chars: &Vec<char>) -> usize {
|
|
let mut iter = chars.iter().enumerate().peekable();
|
|
|
|
for (i, _) in &mut iter {
|
|
let zero = chars.get(i);
|
|
let one = chars.get(i + 1);
|
|
let two = chars.get(i + 2);
|
|
let three = chars.get(i + 3);
|
|
|
|
let mut cursor: Vec<char> = vec![*zero.unwrap(), *one.unwrap(), *two.unwrap(), *three.unwrap()];
|
|
cursor.sort_unstable();
|
|
|
|
// If there's a duplicate character, go forward
|
|
if cursor[0] == cursor[1] || cursor[1] == cursor[2] || cursor[2] == cursor[3] || i < 4 {
|
|
continue;
|
|
}
|
|
|
|
// Since we are looking 3 characters farther than the current iteration,
|
|
// we need to add that to the returned index, plus an extra one, because
|
|
// the array is zero-indexed
|
|
return i + 4;
|
|
}
|
|
|
|
panic!("Marker not found");
|
|
}
|
|
|
|
fn main() {
|
|
let file_str = include_str!("input.txt");
|
|
let chars: Vec<char> = file_str.chars().collect();
|
|
|
|
let chars_before_marker = find_num_chars_before_marker(&chars);
|
|
|
|
println!(
|
|
"Part 1: Number of characters before start-of-packet marker: {}",
|
|
chars_before_marker
|
|
);
|
|
}
|