fn main() {

    start_time();
    let rust_fib_i = rust_fib_i(46);
    let t_rust_fib_i = stop_time();
    result("rust_fib_i", rust_fib_i, t_rust_fib_i);

    start_time();
    let fib_i = itsy_fib_i(46);
    let t_fib_i = stop_time();
    result("fib_i", fib_i, t_fib_i);
    ratio(t_fib_i, t_rust_fib_i);

    start_time();
    let rust_fib_r = rust_fib_r(36);
    let t_rust_fib_r = stop_time();
    result("rust_fib_r", rust_fib_r, t_rust_fib_r);

    start_time();
    let fib_r = itsy_fib_r(36);
    let t_fib_r = stop_time();
    result("fib_r", fib_r, t_fib_r);
    ratio(t_fib_r, t_rust_fib_r);

    start_time();
    let rust_stringcat = rust_stringcat(5000);
    let t_rust_stringcat = stop_time();
    result("rust_stringcat", 0, t_rust_stringcat);

    start_time();
    let stringcat = itsy_stringcat(5000);
    let t_stringcat = stop_time();
    result("itsy_stringcat", 0, t_stringcat);
    ratio(t_stringcat, t_rust_stringcat);
}

fn result(label: String, value: i32, elapsed: f64) {
    print(label + ": " + (value as String) + " in " + (elapsed as String) + "s");
}

fn ratio(itsy: f64, rust: f64) {
    print("ratio: " + ((itsy / rust) as String));
}

fn itsy_fib_r(n: i32) -> i32 {
    if n < 2 {
        n
    } else {
        itsy_fib_r(n - 1) + itsy_fib_r(n - 2)
    }
}

fn itsy_fib_i(n: i32) -> i32 {
    let mut i = 0;
    let mut j = 1;
    let mut k = 1;
    let mut t;
    if n == 0 {
       return 0;
    }
    while k < n {
        t = i + j;
        i = j;
        j = t;
        k += 1;
    }
    return j;
}

fn itsy_stringcat(n: i32) -> String {
    let s = n as String;
    if n > 0 {
        s += itsy_stringcat(n - 1);
    }
    s
}