PAPER 2(exam qs)

Question 1

why does a recursive algorithm take up more storage compared to iterative(2)

Answer 1

• each recursive call creates new variables
• iteration reuses the same variables

Question 2

what must you always do when a stack is full or empty

Answer 2

display message of it being full/empty

Question 3

what are the similarities between classes and records

Answer 3

both store data of different types

Question 4

what is concurrent processing(2)

Answer 4

• processes appear to be happening simultaneously
• giving processes a slice of processor time

Question 5

hwo do we know if data is fully sorted in a bubble sort

Answer 5

if there is no swaps

Question 6

what are the benefits and drawbacks of using iteration compared to recursion

Answer 6

BENEFIT: cannot run out of memory
DRAWBACK: iteration can lead to lengthier code. harder to understand

Question 7

why might insertion sort use less memory compared to merge sort

Answer 7

• merge sort might create a new array each time it splits and merges
• insertion sort doesnt use any new arrays

Question 8

what are error diagnostics

Answer 8

messagesfrom the compiler to the programmer

Question 9

what is thinking ahead

Answer 9

identifying the precondition, inputs and outputs of a system

Question 10

what does openWrite(x.txt) mean

Answer 10

open the file x for writing data

Question 11

what are advantages of pseudocode

Answer 11

• doesn’t matter if it contains syntax errors

Question 12

what is a disadvantage of backtracking

Answer 12

only useful for sequential problems

Question 13

what is the best searching algorithm on average

Answer 13

hashing function

Question 14

what is the difference between get and set methods

Answer 14

• get methods allow attributes to be acessed
• set methods allow attributes to be changed

Question 15

hwo do we know if a linked list is empty

Answer 15

if the head pointer is null

Question 16

what are the 3 benefits of uising OOP

Answer 16

• allow for code reusability
• allows programs to be easier modified and maintained

Question 17

why are things passed by reference(2)

Answer 17

• allows contents to be modified
• uses less memory

Question 18

what has to be implemented into sorting algorithms so they do not tuurn recursive

Answer 18

• set a flag if swaps are made(set it to false)

Question 19

what is problem recognition

Answer 19

identifying requirements to solve a problem

Question 20

what is an operator

Answer 20

a character that represents an action

Question 21

Which data structure is necessary to perform a depth first search of a tree or graph

Answer 21

a stack

Question 22

what is a limitation of performance modelling

Answer 22

• requires accurate data

Question 23

why is heuristics usually applied

Answer 23

when the problem takes too long or too expensivve to achieve

Question 24

what is pattern recognition

Answer 24

when you look for similarities between different problems

Question 25

how can abstraction be used when actually programming a solution

Answer 25

deciding which variables and routines are needed

Question 26

what is parallel processing

Answer 26

when different processing units process diffferent tasks at the same time

Question 27

why are constructors used

Answer 27

to create an instance of an object from a class

Question 28

what is the name given to top classes and under classes

Answer 28

- super class - sub class

Question 29

what is the difference between by reference and by value

Answer 29

- by reference the function receives the memory location of the data - by value the function receives the copy of the variable

Question 30

what is one advantage and disadvantage of using global variables

Answer 30

advantage: can be accessed from anywhere in the program disadvantage: increases memory usage as it is used until full program execution is over

Question 31

what are 2 features which are provided by the IDE which help to write code

Answer 31

- auto complete(fill in the rest when the command is being typed in) - auto indent(indents code to help avoid errors)

Question 32

difference between directed and undireted graphs

Answer 32

- in directed edges may only go in one direction - in undirected edges can go in both directions

Question 33

what are the similarities between A* and Dijkstras(2)

Answer 33

- both are path finding algorithms - both find the shortest route

Question 34

what are the 2 features of any recursive algorithm

Answer 34

- a function that calls itself - has a base case(a condition that terminates the algorithm through furtehr recursions)