71 lines
1.9 KiB
Rust
71 lines
1.9 KiB
Rust
pub fn process_part1(input: &str) -> String {
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let mut password = input.to_string();
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loop {
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password = increment(&password);
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if password.contains("i") || password.contains("o") || password.contains("l") {
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continue;
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}
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if !has_straight(&password) {
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continue;
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}
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if num_pairs(&password) < 2 {
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continue;
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}
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return password;
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}
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}
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fn has_straight(password: &str) -> bool {
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for window in password.as_bytes().windows(3) {
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let (a, b, c) = (window[0], window[1], window[2]);
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let (inc_b, inc_c) = (increment_letter(a), increment_letter(b));
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if b == inc_b.0 && c == inc_c.0 && !(inc_b.1 || inc_c.1) {
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return true;
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}
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}
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false
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}
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fn num_pairs(password: &str) -> u32 {
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let mut num_pairs = 0;
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let mut was_last_pair = false;
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password.as_bytes().windows(2).for_each(|window| {
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if window[0] == window[1] && !was_last_pair {
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num_pairs += 1;
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was_last_pair = true;
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} else {
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was_last_pair = false;
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}
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});
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num_pairs
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}
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fn increment(password: &str) -> String {
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let mut password_bytes = password.as_bytes().to_vec();
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password_bytes.reverse();
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let mut new_password_bytes = vec![];
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let mut increment_next = true;
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for letter in password_bytes {
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if increment_next {
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let (new_letter, overflow) = increment_letter(letter);
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new_password_bytes.push(new_letter);
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increment_next = overflow;
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} else {
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new_password_bytes.push(letter);
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}
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}
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if increment_next {
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new_password_bytes.push(b'a');
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}
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new_password_bytes.reverse();
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String::from_utf8(new_password_bytes).unwrap()
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}
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fn increment_letter(letter: u8) -> (u8, bool) {
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if letter == b'z' {
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(b'a', true)
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} else {
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(letter + 1, false)
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}
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}
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