Computer Science A
2023 FRQ 1
- 2023 FRQ 1: Methods and Control Structures
- Overall Problem Description
- Overall Given Code (Code Runner)
- Code Runner Challenge
- Part (a) Prompt
- Part (a) Code Runner
- Code Runner Challenge
- Part (b) Prompt
- Part (b) Code Runner
- Code Runner Challenge
2023 FRQ 1: Methods and Control Structures
Overall Problem Description
This question involves the AppointmentBook class, which provides methods for students to schedule appointments with their teacher. Appointments can be scheduled during one of eight class periods during the school day, numbered 1 through 8. A requested appointment has a duration, which is the number of minutes the appointment will last. The 60 minutes within a period are numbered 0 through 59. In order for an appointment to be scheduled, the teacher must have a block of consecutive, available minutes that contains at least the requested number of minutes in a requested period. Scheduled appointments must start and end within the same period.
Overall Given Code (Code Runner)
Code Runner Challenge
Starter code for the AppointmentBook class used in all parts.
Part (a) Prompt
Write the findFreeBlock method, which searches period for the first block of free minutes
that is duration minutes long. If such a block is found, findFreeBlock returns the first
minute in the block. Otherwise, findFreeBlock returns -1. The findFreeBlock method
uses the helper method isMinuteFree, which returns true if a particular minute is available to
be included in a new appointment and returns false if the minute is unavailable.
Consider the following list of unavailable and available minutes in period 2.
| Minutes in Period 2 | Available? |
|---|---|
| 0–9 (10 minutes) | No |
| 10–14 (5 minutes) | Yes |
| 15–29 (15 minutes) | No |
| 30–44 (15 minutes) | Yes |
| 45–49 (5 minutes) | No |
| 50–59 (10 minutes) | Yes |
The method call findFreeBlock(2, 15) would return 30 to indicate that a 15-minute block
starting with minute 30 is available. No steps should be taken as a result of the call to
findFreeBlock to mark those 15 minutes as unavailable.
The method call findFreeBlock(2, 9) would also return 30. Whenever there are multiple
blocks that satisfy the requirement, the earliest starting minute is returned.
The method call findFreeBlock(2, 20) would return -1, since no 20-minute block of
available minutes exists in period 2.
Complete method findFreeBlock. You must use isMinuteFree appropriately in order to
receive full credit.
/** *
- Searches for the first block of duration free minutes during period, as described in
- part (a). Returns the first minute in the block if such a block is found or returns -1 if no
- such block is found.
- Preconditions: 1 <= period <= 8; 1 <= duration <= 60 */ public int findFreeBlock(int period, int duration)
Part (a) Code Runner
Code Runner Challenge
Implement `findFreeBlock` to return the first starting minute of a contiguous block of free minutes of length `duration` within the given `period`, or `-1` if none exists. Use `isMinuteFree` to check availability and return the earliest valid start.
Part (b) Prompt
Write the makeAppointment method, which searches the periods from startPeriod to
endPeriod, inclusive, for the earliest block of duration available minutes in the
lowest-numbered period. If such a block is found, the makeAppointment method calls the helper
method reserveBlock to mark the minutes in the block as unavailable and returns true. If no
such block is found, the makeAppointment method returns false.
Consider the following list of unavailable and available minutes in periods 2, 3, and 4 and three
successive calls to makeAppointment.
| Period | Minutes | Available? |
|---|---|---|
| 2 | 0–24 (25 minutes) | No |
| 2 | 25–29 (5 minutes) | Yes |
| 2 | 30–59 (30 minutes) | No |
| 3 | 0–14 (15 minutes) | Yes |
| 3 | 15–40 (26 minutes) | No |
| 3 | 41–59 (19 minutes) | Yes |
| 4 | 0–4 (5 minutes) | No |
| 4 | 5–29 (25 minutes) | Yes |
| 4 | 30–43 (14 minutes) | No |
| 4 | 44–59 (16 minutes) | Yes |
The method call makeAppointment(2, 4, 22) returns true and results in the minutes 5
through 26, inclusive, in period 4 being marked as unavailable.
The method call makeAppointment(3, 4, 3) returns true and results in the minutes 0
through 2, inclusive, in period 3 being marked as unavailable.
The method call makeAppointment(2, 4, 30) returns false, since there is no block of 30
available minutes in periods 2, 3, or 4.
The following shows the updated list of unavailable and available minutes in periods 2, 3, and 4 after the three example method calls are complete.
| Period | Minutes | Available? |
|---|---|---|
| 2 | 0–24 (25 minutes) | No |
| 2 | 25–29 (5 minutes) | Yes |
| 2 | 30–59 (30 minutes) | No |
| 3 | 0–2 (3 minutes) | No |
| 3 | 3–14 (12 minutes) | Yes |
| 3 | 15–40 (26 minutes) | No |
| 3 | 41–59 (19 minutes) | Yes |
| 4 | 0–26 (27 minutes) | No |
| 4 | 27–29 (3 minutes) | Yes |
| 4 | 30–43 (14 minutes) | No |
| 4 | 44–59 (16 minutes) | Yes |
Complete method makeAppointment. Assume that findFreeBlock works as intended,
regardless of what you wrote in part (a). You must use findFreeBlock and reserveBlock
appropriately in order to receive full credit.
/** *
- Searches periods from startPeriod to endPeriod, inclusive, for a block
- of duration free minutes, as described in part (b). If such a block is found,
- calls reserveBlock to reserve the block of minutes and returns true; otherwise
- returns false.
- Preconditions: 1 <= startPeriod <= endPeriod <= 8; 1 <= duration <= 60 */ public boolean makeAppointment(int startPeriod, int endPeriod, int duration)
Part (b) Code Runner
Code Runner Challenge
Implement `makeAppointment` to search periods `startPeriod` through `endPeriod` for the earliest block of `duration` free minutes in the lowest-numbered period. If found, call `reserveBlock` to mark the block and return `true`; otherwise return `false`. Assume `findFreeBlock` works as intended.