Treatment Frequency Scheduler

Requirements

• Represent a treatment whose recurrence interval can be configured, such as once every 4 hours, once every 12 hours, or once per day at 9 AM.
• For a treatment and an inclusive date interval [start, end], return every scheduled treatment time that lies in that interval.
• A patient may have several treatments, and the combined results must support sorting and grouping by patient.
• The interviewer does not evaluate the exact date-arithmetic syntax; date calculations may be left as comments. The main evaluation criterion is the logical organization of the classes.

Examples

Example 1

Input: A treatment anchored at 4:00 AM, repeating every 4 hours, queried over a 24-hour range ending at midnight.

Output: Six occurrence times: 4:00 AM, 8:00 AM, noon, 4:00 PM, 8:00 PM, and midnight.

The recurrence advances by 4 hours, and these six generated times are the ones that fall within the requested range.

Example 2

Input: A treatment anchored at 9:00 AM, repeating every day, queried from 9:00 AM on one day through 9:00 AM two days later.

Output: The treatment time at 9:00 AM on each of those three days.

Each occurrence is separated from the previous one by one day, and the boundary times are included in the range.