Help with regex

I am dealing with a patient day calendar with time slots. Each hour is divided into two equal time slots. If the person is available for the whole 1 hour it is is denoted as 11 If not available for the whole hour : 00 Available for first half only : 10 Available for second half only : 01 So the entire calendar of the patient has 48 digits But for now, just to ease things, we will assume we are looking from 12AM to 6AM only. So the calendar will be [01]{12} Suppose the patient is available from 12AM to 3AM and 4AM to 6AM. Now his calendar can be marked as 111111001111 Now the doctors' calendar is also stored in the similar way Now suppose the appointment window is fixed as 1 hour, I need to find all the doctors has a 1 hour available timeslots within patient's available timeslot The doctors' availability outside the patient's available time doesn't matter, ie in this case 3AM to 4AM Basically, I want to write a regex to match all those