Number of students doing homework at a given time

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

#[test]
fn t2() {
    let start = std::time::Instant::now();
    let val = Solution::busy_student(vec![4], vec![4], 4);
    let expected = 1;
    log_result!(val == expected, "t2", start, &expected, &val);
    assert_eq!(val, expected);
}

#[test]
fn t3() {
    let start = std::time::Instant::now();
    let val = Solution::busy_student(vec![1, 1, 1, 1], vec![1, 3, 2, 4], 7);
    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::busy_student(vec![9, 8, 7, 6, 5, 4, 3, 2, 1], vec![10, 10, 10, 10, 10, 10, 10, 10, 10], 5);
    let expected = 5;
    log_result!(val == expected, "t4", start, &expected, &val);
    assert_eq!(val, expected);
}

#[test]
fn t5() {
    let start = std::time::Instant::now();
    let val = Solution::busy_student(vec![1, 2, 3], vec![3, 2, 7], 2);
    let expected = 2;
    log_result!(val == expected, "t5", start, &expected, &val);
    assert_eq!(val, expected);
}