Subarray sums divisible by k

#[test]
fn t1() {
    let start = std::time::Instant::now();
    let val = Solution::subarrays_div_by_k(vec![4, 5, 0, -2, -3, 1], 5);
    let expected = 7;
    log_result!(val == expected, "t1", start, &expected, &val);
    assert_eq!(val, expected);
}

#[test]
fn t2() {
    let start = std::time::Instant::now();
    let val = Solution::subarrays_div_by_k(vec![5], 9);
    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::subarrays_div_by_k(vec![0], 1);
    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::subarrays_div_by_k(vec![1, 2, 3], 3);
    let expected = 3;
    log_result!(val == expected, "t4", start, &expected, &val);
    assert_eq!(val, expected);
}

#[test]
fn t5() {
    let start = std::time::Instant::now();
    let val = Solution::subarrays_div_by_k(vec![-1, 2, 9], 2);
    let expected = 2;
    log_result!(val == expected, "t5", start, &expected, &val);
    assert_eq!(val, expected);
}