CODEWITHSUNDEEP
algorithmcalendarlanguage-agnostic
Jaden Baptista
Jaden Baptista

Reputation: 736

Algorithm for Scheduling One Appointment in Already Full Schedule

I'm building a calendar scheduling application for, let's say a plumbing company. The company has one or more plumbers, who each have a schedule of appointments at different times throughout the day. So Josh's schedule on May 30th might include a 30-minute appointment at 10 AM, a 45-minute appointment at 1 PM, and an hour-long appointment at 3 PM, while Maria has a completely different schedule that day. Now say a customer wants to book an appointment with this company, and my program has already calculated the time this new appointment will take. I want my program to return a list of possible appointment times for any plumber(s). Is there a standard algorithm for this type of problem?

I'd prefer language-agnostic, general steps just to be more helpful to anyone who might be in a similar situation with a different language, though I'm using PHP and PostgreSQL if there's a specific language feature suited to this.

Here's what I've tried so far:

  1. Get all available shifts for every plumber on the requested day
  2. Get all appointments already made on that day
  3. Do a sort of boolean subtraction to cut the appointments out of the shifts, leaving gaps in each plumber's schedule
  4. Get rid of all schedule gaps that are smaller than the requested appointment length (I also calculate drive times here so I know how far appointments need to be from one another)
  5. Return those gaps to the customer, trimmed to the appointment length, as appointment possibilities

I've learned that the problem with this approach is that it doesn't understand what to do with a gap much larger than the requested appointment. If you have a gap from 10 AM to 6 PM but you want an hour-long appointment, it will only suggest 10 AM to 11 AM. This approach doesn't allow for time-of-day choices, either. In that same scenario, what if the customer wants a morning appointment? Then it should only suggest 10-11 and 11-12. Or if they want an evening appointment, it should only suggest 5-6 PM. This approach also doesn't consider two plumbers working together. If we assume that two workers = half the time, then maybe the algorithm should look for the same 30 minutes available in both Josh and Maria's schedules along with 60-minute gaps in either plumber's schedule. Lastly, this algorithm feels very inefficient.

By the way, I've looked at several other questions here and around the Internet about how to solve similar situations, but I'm finding that most (if not all) of those questions involve optimizing a schedule. That might be valuable for other parts of this program, but for now, let's assume that the existing appointments are fixed and unchangeable. We're just looking to fit a new appointment into an existing schedule. I know this is possible because applications like Calendly have similar inputs and outputs.

In short, is there a better way of meeting these goals:

Thank you in advance.

Upvotes: 3

Views: 865

Answers (1)

pentadecagon
pentadecagon

Reputation: 4847

There is no need for any sophisticated algorithm. There is only a small number of possible appointment times throughout a day, let's say every 30 minutes or so. Iterate over all possible times: 06:00, 06:30, 07:00, ... 20:00. Check each time if it matches the requirements, that check can either return a yes/no result, or a number that say how good a match that time is. You end up with a list of possible appointment times, pick the best one or all of them.

Upvotes: 2

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