Number of subarrays having even product

#[test]
fn t1() {
    let start = std::time::Instant::now();
    let val = Solution::even_product(vec![9, 6, 7, 13]);
    let expected = 6;
    log_result!(val == expected, "t1", start, &expected, &val);
    assert_eq!(val, expected);
}

#[test]
fn t2() {
    let start = std::time::Instant::now();
    let val = Solution::even_product(vec![7, 3, 5]);
    let expected = 0;
    log_result!(val == expected, "t2", start, &expected, &val);
    assert_eq!(val, expected);
}

#[test]
fn t3() {
    let start = std::time::Instant::now();
    let val = Solution::even_product(vec![2]);
    let expected = 1;
    log_result!(val == expected, "t3", start, &expected, &val);
    assert_eq!(val, expected);
}

#[test]
fn t4() {
    let start = std::time::Instant::now();
    let val = Solution::even_product(vec![1, 2, 3]);
    let expected = 4;
    log_result!(val == expected, "t4", start, &expected, &val);
    assert_eq!(val, expected);
}

#[test]
fn t5() {
    let start = std::time::Instant::now();
    let val = Solution::even_product(vec![2, 2, 2]);
    let expected = 6;
    log_result!(val == expected, "t5", start, &expected, &val);
    assert_eq!(val, expected);
}