main.rs

use std::{ io::{ stdin, stdout, Write } };

fn main() {
    let mut input = String::new();

    print!("Please enter the sentence: ");
    stdout().lock().flush().expect("Could not write the prompt");

    stdin().read_line(&mut input).expect("Could not get input");

    println!("{}", is_pangram(input.trim()))
}

fn is_pangram(input: &str) -> bool {
    let mut letters: u32 = 0;

    for character in input.chars() {
        let letter = character as u32;

        letters =
            letters |
            (1 <<
                (if letter <= 90 && letter >= 65 {
                    // capital letters
                    letter - 65
                } else if letter <= 122 && letter >= 97 {
                    // lowercase letters
                    letter - 97
                } else {
                    continue;
                }));
    }

    letters == 67108863
}