ROT13 in Python and Rust

rot13.py

#!/usr/bin/env python3
# -*- coding: utf8 -*-
import sys


def generate_table() -> dict[str, str]:
    """
    Generates a look up table for mapping characters to their ROT13 character.
    """
    input = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
    output = "NOPQRSTUVWXYZABCDEFGHIJKLMnopqrstuvwxyzabcdefghijklm"

    return dict(zip(input, output))


def main() -> None:
    if len(sys.argv) < 2:
        print("Usage: rot13.py <string>")
        sys.exit(1)

    string = " ".join(sys.argv[1:])
    lookup_table = generate_table()
    output = "".join(map(lambda c: lookup_table.get(c, c), string))

    print(output)


if __name__ == "__main__":
    main()

rot13.rs

//! ROT13 (Rotate13, "rotate by 13 places", sometimes hyphenated ROT-13) is a
//! simple letter substitution cipher that replaces a letter with the 13th letter after it in the Latin alphabet.
//! ROT13 is a special case of the Caesar cipher which was developed in ancient Rome.
//! 
//! Because there are 26 letters (2×13) in the basic Latin alphabet,
//! ROT13 is its own inverse; that is, to undo ROT13, the same algorithm is applied,
//! so the same action can be used for encoding and decoding.
//! The algorithm provides virtually no cryptographic security,
//! and is often cited as a canonical example of weak encryption.
//! 
//! ROT13 has been used in online forums as a means of hiding spoilers,
//! punchlines, puzzle solutions, and offensive materials from the casual glance.
//! ROT13 has inspired a variety of letter and word games online, and is frequently mentioned in newsgroup conversations.
//! 
//! https://en.wikipedia.org/wiki/ROT13
use std::collections::HashMap;
use std::env;
use std::process;

fn generate_table() -> HashMap<char, char> {
    let input = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
    let output = "NOPQRSTUVWXYZABCDEFGHIJKLMnopqrstuvwxyzabcdefghijklm";

    input.chars().zip(output.chars()).collect()
}

fn main() {
    let args: Vec<String> = env::args().collect();

    if args.len() < 2 {
        eprintln!("Usage: rot13 <string>");
        process::exit(1);
    }

    let input = args[1..].join(" ");
    let lookup_table = generate_table();
    let output: String = input
        .chars()
        .map(|c| lookup_table.get(&c).copied().unwrap_or(c))
        .collect();

    println!("{}", output);
}