Computer Science · Oct / Nov 2023 · Paper 21 · Question 10
0478
As printed in the paper
The question as text
Drama students put on a performance of a play for one evening. Seats in a small theatre can be booked for this performance. The theatre has 10 rows of 20 seats. The status of the seat bookings for the evening is held in the tw Evening[] Each element contains FALSE if the seat is available and TRUE if the seat is booked. Up to and including four seats can be booked at one time. Seats are allocated in order from those available. A row or seat number cannot be requested. The array Evening[] has already been set up and some data stored. Write a program that meets the following requirements: • counts and outputs the number of seats already booked for the evening • allows the user to input the number of seats required • validates the input • checks if enough seats are available: – if they are available ○ changes the status of the seats ○ outputs the row number and seat number for each seat booked – if they are not available: ○ outputs a message giving the number of seats left or ‘House full’ if the theatre is fully bo You must use pseudocode or program code and add comments to explain how your code works. You do not need to declare any arrays or variables; you may assume that this has already been done. You do not need to initialise the data in the array Evening[] All inputs and outputs must contain suitable messages.
Read automatically from the paper; the printed page above is exact.
Show the answer and mark scheme
Data Structures required names shown underlined must be used as given in the scenario
2D Array or list Evening[1:10, 1:20] / Evening[0:9, 0:19]
Variables Counter, SeatCounter, NumSeats, Row, Column
Requirements (techniques)
R1 Find number of seats available for each performance and output (searching, nested iteration, output)
R2 Inputs and validates number of seats (input, iteration, and selection)
R3 Checking if seats available (selection, assignment, output with appropriate messages)
Example 15-mark answer in pseudocode
// meaningful identifier names and appropriate data structures to store the data required DECLARE Counter, SeatCounter, NumSeats, Row, Column : INTEGER
CONSTANT HouseFull = 200
CONSTANT MaxRow = 10
CONSTANT MaxColumn = 20
SeatCounter1 ← 0 // initialise seat counter for performance 1
FOR Row ← 1 TO 10
FOR Column ← 1 TO 20
IF Evening[Row, Column]
THEN
SeatCounter ← SeatCounter + 1
ENDIF
NEXT Column
NEXT Row
// validate input
OUTPUT "How many seats do you want to book? 1, 2, 3 or 4 "
INPUT NumSeats
WHILE 1 < NumSeats OR NumSeats > 4 OR NumSeats <> ROUND(NumSeats, 0)
OUTPUT "Please enter 1, 2, 3 or 4 for the number of seats "
INPUT NumSeats
ENDWHILE
IF SeatCounter + NumSeats > 200)// check for house full
THEN
OUTPUT "House full"
ELSE
IF SeatCounter + NumSeats > 200 // checks for not enough seats
THEN
OUTPUT "Only ", SeatCounter + NumSeats – 200, " seats left"
ELSE
FOR Counter ← 1 TO NumSeats // book required number of seats for performance Evening[MOD(SeatCounter + Counter, MaxColumn), DIV(SeatCounter + Counter), MaxColumn] ← TRUE
OUTPUT "Row ", MOD(SeatCounter + Counter, MaxColumn), " seat ",
DIV(SeatCounter + Counter, MaxColumn)," booked"
NEXT Counter
ENDIF
AO2:
Apply knowledge and understanding of the principles and concepts of computer science to a given context, including the analysis and design of computational or programming problems
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