problem35.rs

use std::num;

fn is_prime(number: int) -> bool {
    for i in range(2, ((number as f64).sqrt() as int) + 1) {
        if number % i == 0 {
            return false
        }
    }

    true
}

fn is_circular_prime(number: int) -> bool {
    if !is_prime(number) {
        return false
    }

    let mut places = 1;

    while (number / num::pow(10, places)) > 0 {
        places += 1;
    }

    let mut check = number;

    for i in range(0, places) {
        if i > 0 && !is_prime(check) {
            return false
        }

        check = (check / 10) + ((check % 10) * num::pow(10, places - 1));
    }

    true
}

fn main() {
    let mut count = 0;

    for i in range(2, 1000000) {
        if is_circular_prime(i) {
            count += 1;
        }
    }

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