51 lines
1.5 KiB
Rust
51 lines
1.5 KiB
Rust
fn find_num_chars_before_marker(chars: &Vec<char>, marker_size: usize) -> usize {
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let mut iter = chars.iter().enumerate();
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'outer: for (i, _) in &mut iter {
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// Look marker_size -1 characters forward so we can check for duplicate characters
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let mut cursor: Vec<char> = Vec::new();
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for n in 0..marker_size {
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cursor.push(*chars.get(i + n).unwrap());
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}
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cursor.sort_unstable();
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// If there's a duplicate character, go forward
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for (n, ch) in cursor.iter().enumerate() {
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if let Some(other) = cursor.get(n + 1) {
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if ch == other {
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continue 'outer;
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}
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}
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}
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// Since we are looking farther than the current iteration,
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// we need to add the marker size that to the returned index
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return i + marker_size;
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}
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panic!("Marker not found");
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}
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fn find_packet_marker(chars: &Vec<char>) -> usize {
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find_num_chars_before_marker(chars, 4)
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}
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fn find_message_marker(chars: &Vec<char>) -> usize {
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find_num_chars_before_marker(chars, 14)
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}
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fn main() {
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let file_str = include_str!("input.txt");
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let chars: Vec<char> = file_str.chars().collect();
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println!(
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"Part 1: Number of characters before start-of-packet marker: {}",
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find_packet_marker(&chars)
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);
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println!(
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"Part 2: Number of characters before start-of-message marker: {}",
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find_message_marker(&chars)
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);
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}
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