A linear queue is implemented using the 1D array, Queue. The index of the first element in the array is 0.

1. (a)(i)Write program code to declare: • Queue — a global array with space to store 50 IDs of type string • HeadPointer — a global variable to point to the first element in the queue, initialised to -1 • TailPointer — a global variable to point to the next available space in the queue, initialised to 0. Save your program as Question2_N23. Copy and paste the program code into part 2(a)(i) in the evidence document.[2]
2. (a)(ii)The procedure Enqueue () takes a string parameter. If the queue is full, the procedure outputs a suitable message. If the queue is not full, the procedure inserts the parameter into the queue and updates the relevant pointer(s). Write program code for Enqueue(). Save your program. Copy and paste the program code into part 2(a)(ii) in the evidence document.[4]
3. (a)(iii)The function Dequeue() checks if the queue is empty. If the queue is empty, the function outputs a suitable message and returns the string "Empty". If the queue is not empty, the function returns the first element in the queue and updates the relevant pointer(s). Write program code for Dequeue(). Save your program. Copy and paste the program code into part 2(a)(iii) in the evidence document.[4]
4. (b)A shop sells computer games. Each game has a unique identifier (ID) of string data type. The text file QueueData.txt contains a list of game IDs. The procedure ReadData() reads the data from the text file and inserts each item of data into the array Queue. Write program code for the procedure ReadData(). Save your program. Copy and paste the program code into part 2(b) in the evidence document.[6]
5. (c)(i)Some game IDs appear in the text file more than once. The program needs to total the number of times each game ID appears in the text file. The record structure RecordData has the following fields: • ID — a string to store the game ID • Total — an integer to store the total number of times that game ID appears in the text file. Write program code to declare the record structure RecordData. If you are writing in Python, include attribute declarations as comments. Save your program. Copy and paste the program code into part 2(c)(i) in the evidence document.[2]
6. (c)(ii)The global 1D array Records stores up to 50 items of type RecordData. The global variable NumberRecords stores the number of records currently in the array Records and is initialised to 0. Write program code to declare Records and NumberRecords. If you are writing in Python, include attribute declarations as comments. Save your program. Copy and paste the program code into part 2(c)(ii) in the evidence document.[2]
7. (c)(iii)The pseudocode algorithm for the procedure TotalData(): • uses Dequeue () to remove an ID from the queue • checks whether a RecordData with the returned ID exists in Records • increments the total for that ID in the record if the ID already exists • creates a new record and stores it in Records if the ID does not exist. PROCEDURE TotalData() DECLARE DataAccessed : STRING DECLARE Flag : BOOLEAN DataAccessed ← Dequeue() Flag ← FALSE IF NumberRecords = 0 THEN Records[NumberRecords].ID ← DataAccessed Records[NumberRecords].Total ← 1 Flag ← TRUE NumberRecords ← NumberRecords + 1 ELSE FOR X ← 0 TO NumberRecords – 1 IF Records[X].ID = DataAccessed THEN Records[X].Total ← Records[X].Total + 1 Flag ← TRUE ENDIF NEXT X ENDIF IF Flag = FALSE THEN Records[NumberRecords].ID ← DataAccessed Records[NumberRecords].Total ← 1 NumberRecords ← NumberRecords + 1 ENDIF ENDPROCEDURE Write program code for the procedure TotalData(). Save your program. Copy and paste the program code into part 2(c)(iii) in the evidence document.[5]
8. (d)The procedure OutputRecords() outputs the ID and total of each record in Records in the format: ID 1234 Total 4 Write program code for OutputRecords(). Save your program. Copy and paste the program code into part 2(d) in the evidence document.[1]
9. (e)(i)The main program needs to: • call ReadData() • call TotalData() for each element in the queue • call OutputRecords(). Write program code for the main program. Save your program. Copy and paste the program code into part 2(e)(i) in the evidence document.[2]
10. (e)(ii)Test your program. Take a screenshot of the output. Save your program. Copy and paste the screenshot into part 2(e)(ii) in the evidence document.[1]