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use std::collections::HashSet;
fn main() {
let input = "hxbxwxba";
println!("11a: {}", next_password(input));
println!("11b: {}", next_password(&next_password(input)));
}
fn has_straight(password: &str) -> bool {
let mut prevprev = password.chars().next().unwrap().to_digit(36).unwrap();
let mut prev = password.chars().nth(1).unwrap().to_digit(36).unwrap();
for c in password.chars().skip(2) {
let digit = c.to_digit(36).unwrap();
if prevprev + 1 == prev && prev + 1 == digit {
return true;
}
prevprev = prev;
prev = digit;
}
false
}
fn has_forbidden_letters(password: &str) -> bool {
password.contains('i') || password.contains('o') || password.contains('l')
}
fn has_two_pairs(password: &str) -> bool {
let mut pairs = HashSet::new();
let mut prev = password.chars().next().unwrap();
for c in password.chars().skip(1) {
if prev == c {
pairs.insert(c);
}
prev = c;
}
pairs.len() > 1
}
fn valid_password(password: &str) -> bool {
has_straight(password) && !has_forbidden_letters(password) && has_two_pairs(password)
}
fn inc_password_at_position(password: &str, pos: usize) -> String {
let mut bytes = password.to_string().into_bytes();
bytes.reverse();
bytes[pos] += 1;
if bytes[pos] > b'z' {
bytes[pos] = b'a';
bytes.reverse();
let new_password = String::from_utf8(bytes.to_vec()).unwrap();
inc_password_at_position(&new_password, pos + 1)
} else {
bytes.reverse();
String::from_utf8(bytes.to_vec()).unwrap()
}
}
fn next_password(password: &str) -> String {
let mut password = inc_password_at_position(password, 0);
while !valid_password(&password) {
password = inc_password_at_position(&password, 0)
}
password
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test() {
assert!(!valid_password("hijklmmn"));
assert!(!valid_password("abbceffg"));
assert!(!valid_password("abbcegjk"));
assert_eq!(next_password("abcdefgh"), "abcdffaa");
assert_eq!(next_password("ghijklmn"), "ghjaabcc");
}
}
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