Maximum strength of a group

#[test]
fn t1() {
    let start = std::time::Instant::now();
    let val = Solution::max_strength(vec![3, -1, -5, 2, 5, -9]);
    let expected = 1350;
    log_result!(val == expected, "t1", start, &expected, &val);
    assert_eq!(val, expected);
}

#[test]
fn t2() {
    let start = std::time::Instant::now();
    let val = Solution::max_strength(vec![-4, -5, -4]);
    let expected = 20;
    log_result!(val == expected, "t2", start, &expected, &val);
    assert_eq!(val, expected);
}

#[test]
fn t3() {
    let start = std::time::Instant::now();
    let val = Solution::max_strength(vec![0, -1]);
    let expected = 0;
    log_result!(val == expected, "t3", start, &expected, &val);
    assert_eq!(val, expected);
}

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

#[test]
fn t5() {
    let start = std::time::Instant::now();
    let val = Solution::max_strength(vec![2, 3, 4]);
    let expected = 24;
    log_result!(val == expected, "t5", start, &expected, &val);
    assert_eq!(val, expected);
}

#[test]
fn t6() {
    let start = std::time::Instant::now();
    let val = Solution::max_strength(vec![-9, -9, 9, 0]);
    let expected = 729;
    log_result!(val == expected, "t6", start, &expected, &val);
    assert_eq!(val, expected);
}