criterion 0.1.1

use criterion::Criterion;
use criterion::Fun;

fn fibonacci_slow(n: u64) -> u64 {
    match n {
        0 | 1 => 1,
        n => fibonacci_slow(n-1) + fibonacci_slow(n-2),
    }
}

fn fibonacci_fast(n: u64) -> u64 {
    let mut a = 0u64;
    let mut b = 1u64;
    let mut c : u64;

    if n == 0 {
        return 0
    }

    for _ in 0..(n+1) {
        c = a + b;
        a = b;
        b = c;
    }
    b
}

fn compare_fibonaccis(c: &mut Criterion) {
    let fib_slow = Fun::new("Recursive", |b, i| b.iter(|| fibonacci_slow(*i)));
    let fib_fast = Fun::new("Iterative", |b, i| b.iter(|| fibonacci_fast(*i)));

    let functions = vec!(fib_slow, fib_fast);
    
    c.bench_functions("Fibonacci", functions, &20);
}

criterion_group!(fibonaccis, compare_fibonaccis);