diamond.rs

// Diamond Kata

fn main() {
    let character = &std::env::args().collect::<Vec<String>>()[1];
    diamond(character.chars().next().unwrap() as u8)
}

fn diamond(c: u8) {
    let max_rows = c - b'A';
    let mut rows = Vec::with_capacity(max_rows as usize);

    for i in 0..max_rows + 1 {
        let character = (b'A' + i) as char;
        let padding = max_rows - i + 1;
        let mut spacing = 0;
        let row: String;

        if i > 0 {
            spacing = (2 * i - 1) as usize;
        }

        if i == 0 {
            let padding_rhs = padding - 1;
            row = format!(
                "{:>padding$}{:<padding_rhs$}",
                character,
                "",
                padding = padding as usize,
                padding_rhs = padding_rhs as usize
            );
        } else {
            row = format!(
                "{:>padding$}{:^spacing$}{:<padding$}",
                character,
                "",
                character,
                padding = padding as usize,
                spacing = spacing,
            );
        }

        println!("{}", row);
        if i != max_rows {
            rows.push(row);
        }
    }

    for row in rows.iter().rev() {
        println!("{}", row);
    }
}