Different data structures will be suitable for different computing applications. Identify a computing application where a queue data structure is suitable.

Answer

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7(a)(ii)Stacks QueuesMedium2 marks

Justify why a queue is suitable for your application identified in 7(a)(i).

Answer

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7(b)(i)Stacks QueuesEasy2 marks

A programmer designs a circular queue.

The data items are stored in a 1D array, MyQueue
The queue is managed using two pointers.

The diagram shows the circular queue populated with four items.

MyQueue — four items stored

Index	Value	Pointer
1	"PIG"	Front
2	"DOG"
3	"RAT"
4	"SPIDER"	Rear
5
6
7
8

Write three pseudocode declaration statements to implement this circular queue.

Declare the array

Declare the two pointers

7(b)(ii)Stacks QueuesMedium2 marks

Two program modules are available to add and remove items to and from the queue.

module	description
EnQueue()	when is added to the queue
DeQueue()	when an item is removed from the queue

Complete the state of MyQueue after the following sequence of changes:

DeQueue()
EnQueue("HORSE")
EnQueue("CAT")

Index	Value	Pointer
1	Table answer row1_Value	Table answer row1_Pointer
2	Table answer row2_Value	Table answer row2_Pointer
3	Table answer row3_Value	Table answer row3_Pointer
4	Table answer row4_Value	Table answer row4_Pointer
5	Table answer row5_Value	Table answer row5_Pointer
6	Table answer row6_Value	Table answer row6_Pointer
7	Table answer row7_Value	Table answer row7_Pointer
8	Table answer row8_Value	Table answer row8_Pointer

7(b)(iii)Stacks QueuesHard2 marks

On a different occasion, the state of MyQueue is:

Index	Value	Pointer
1
2
3
4	"LION"	Front
5	"GIRAFFE"
6	"TIGER"
7	"ANT"	Rear
8

Complete the state of MyQueue after the following sequence of changes:

EnQueue("GERBIL")
EnQueue("MONKEY")
EnQueue("SNAKE")
DeQueue()

Index	Value	Pointer
1	Table answer row1_Value	Table answer row1_Pointer
2	Table answer row2_Value	Table answer row2_Pointer
3	Table answer row3_Value	Table answer row3_Pointer
4	Table answer row4_Value	Table answer row4_Pointer
5	Table answer row5_Value	Table answer row5_Pointer
6	Table answer row6_Value	Table answer row6_Pointer
7	Table answer row7_Value	Table answer row7_Pointer
8	Table answer row8_Value	Table answer row8_Pointer

7(c)Stacks QueuesMedium3 marks

MyQueue will be initially empty. Write a pseudocode procedure InitialiseQueue() to set up the empty MyQueue, using a loop. The initial array contents will be set to empty strings. You are not required to repeat the declaration statements in 7(b)(i).

text

01PROCEDURE InitialiseQueue()02   …03ENDPROCEDURE

Write the body of InitialiseQueue()

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