extern crate libc; // 0.2.43

use libc::putchar;

fn main() {
    draw_table(2);
    draw_table(5);
    draw_table(10);
}

fn draw_table(num: usize) {
    let sum = num * num;
    let num_digits = count_digits(sum);

    for ref row in 0..=num {
        for ref col in 0..=num {
            let cur_sum = row * col;
            unsafe {
                for _i in 0..=(num_digits - count_digits(cur_sum)) {
                    putchar(32);
                }

                print_number(cur_sum);

                if col < &num {
                    putchar(',' as i32);
                }
            }
        }

        unsafe {
            putchar(10);
        }
    }
}

fn count_digits(mut num: usize) -> u32 {
    let mut count: u32 = 0;
    if num != 0 {
        while num > 0 {
            num /= 10;
            count += 1;
        }
    } else {
        count = 1;
    }

    count
}

fn print_number(num: usize) {
    if num >= 10 {
        print_number(num / 10);
    }

    unsafe {
        putchar((num % 10) as i32 + 48);
    }
}