lib.rs

/// While the problem description indicates a return status of 1 should be returned on errors,
/// it is much more common to return a `Result`, so we provide an error type for the result here.
#[derive(Debug, Eq, PartialEq)]
pub enum AffineCipherError {
    NotCoprime(i32),
}

/// Encodes the plaintext using the affine cipher with key (`a`, `b`). Note that, rather than
/// returning a return code, the more common convention in Rust is to return a `Result`.
pub fn encode(plaintext: &str, a: i32, b: i32) -> Result<String, AffineCipherError> {
    todo!("Encode {plaintext} with the key ({a}, {b})");
}

/// Decodes the ciphertext using the affine cipher with key (`a`, `b`). Note that, rather than
/// returning a return code, the more common convention in Rust is to return a `Result`.
pub fn decode(ciphertext: &str, a: i32, b: i32) -> Result<String, AffineCipherError> {
    todo!("Decode {ciphertext} with the key ({a}, {b})");
}