Exam 2

Question 1

What is a precondition for a binary search?

Answer 1

The data must be in order

Question 2

How does linear search work?

Answer 2

compare the first item with the search value
then compare next item with the search value
repeat process until end of array
to repeat process until the search item has been found and stopped
return the array position

Question 3

What is the difference between passing a parameter by value and by reference?

Answer 3

By reference receives a memory location yet by value receives a copy of the variable

Question 4

What is one benefit and one drawback of using global variables instead of local?

Answer 4

Can be accessed by any function
More memory used

Question 5

Describe a feature of IDE’s that can be helped to write and test programs

Answer 5

Write:
Auto complete- can help fill in the rest
Testing:
Breakpoints- can stop the code at times to check values of variables

Question 6

Why is an integer value used in an array instead of seperate variables

Answer 6

Numbers can be passed in as a single parameter

Question 7

How can caching be used in a plane simulation?

Answer 7

Store frequently use data in the cache ( quicker memory) such as the weather

Question 8

What is a difference between a data tree and a graph data structure?

Answer 8

Graphs don’t have a root node

Question 9

Why is performance modelling used to test a system?

Answer 9

It is more expensive to test a system

Question 10

How would you create a 2D array for cards?

Answer 10

cards = [][]

Question 11

Table question:

Answer 11

5-4-3-2-1
5-4-3-2-1
start from bottom then add up all of the numbers 1+2+3+4+5

Question 12

OOP code add in?

Answer 12

0
-1
-1
pointerValue
returnValue

Question 13

Pseudocode for program stack?

Answer 13

True
push
false
print

Question 14

How can an array be used to implement a queue data structure?

Answer 14

Queue has head pointer and tail pointer
When an item is enqueued the tail pointer increments
When an item is dequeued the head pointer increments

Question 15

Breadth first vs depth first AO1?

Answer 15

Breadth: check top node then visits all nodes connecting to it, then all the nodes connecting to them
Depth: Visits far bottom left node- returns in then checks the one to its right, does all lf them then goes up and across

Question 16

Breadth vs depth AO2?

Answer 16

Do the breadth vs depth searches

Question 17

Breadth vs depth AO3?

Answer 17

Breadth more efficient when it’s closer to the root
Depth more efficient when data is further down
In large trees depth may not even return a value

Question 18

Why are integers value passed as an array?

Answer 18

Can be passed as a single variable

Question 19

Bubble sort code?

Answer 19

50
-2
temp value
y
temp value

Question 20

Bubble vs merge vs insertion AO1?

Answer 20

Merge sort splits data into individual lists
Bubble sort compares one to next
Insertion sort makes new list and adds in

Question 21

Bubble vs merge vs insertion AO2?

Answer 21

Insertion and bubble average O(n^2)
Insertion and bubble best O(n)
Merge average same as merge best
Merge always O(n log n)

Question 22

Bubble vs insertion vs merge AO3?

Answer 22

Small number of elements so bubble and insertion best storage wise
Small number of elements so not very many merge sub lists storage wise
Bubble and insertion both best time complexity wise as small number of elements

Question 23

Difference between A* and Dijkstras?

Answer 23

A* uses heuristics

Question 24

How can an array be used to implement a queue data structure?

Answer 24

Queue has a pointer and tail pointer
when an item is added to queue the tail pointer increments
when an item is removed from the queue the pointer increments

Question 25

OOP vs procedural AO1?

Answer 25

OOP defines an object as an entity
Oop defines attributes of the object and then the methods they can be used in
Attributes can be private to stop accidental changes
Procedural statements are executed as they are written

Question 26

OOP vs procedural AO2?

Answer 26

OOP allowed an object to be created for the queue
This can be repeated very easily by being declared in the main program
Procedural every queue needs to be declared individually

Question 27

OOP vs procedural AO3?

Answer 27

OOP can create multiple instances of the queue without having to repeat the code every time
OOP less code required so fewer errors as only written once
Procedural would require global variables for ease which is more storage