Unit 2 - Problem Solving

Question 1

What is computational thinking?

Answer 1

The ability to think logically about a problem and apply techniques for solving it

Question 2

What are the 5 main ways to solve a problem?

Answer 2

1. Enumeration (list all cases)
2. Simulation
3. Theoretical approach
4. Creative approach
5. Trial and error

Question 3

What does simulation involve?

Answer 3

Designing a model for a system in order to understand its behaviour and then testing it to observe how the system responds to different situation

Question 4

What does enumeration involve?

Answer 4

Running every possible solution until there is one that works

Question 5

What does the decrease and conquer approach to algorithm design involve?

Answer 5

Breaking down a problem into smaller sub-problems which can be tackled individually and then applied to the greater problem

Question 6

What is an algorithm?

Answer 6

A sequence of steps that can be followed to complete a task and always terminates

Question 7

What does a good algorithm need to do?

Answer 7

1. Have a clear set of steps which produces a successful outcome for any set of inputs
2. Allows for invalid inputs
3. Terminate
4. Efficiently achieve the outcome in as few steps as possible
5. Be designed in a way that it can be understood and edited by others

Question 8

What do hierarchy charts do?

Answer 8

Break down a bigger problem into smaller subtasks, a visual representation of decomposition

Question 9

What does an insertion sort entail?

Answer 9

Removing an item and replacing it in the correct position within the set

Question 10

What type of sets is an insertion sort suited to?

Answer 10

Small sets

Question 11

When is bubble sort used?

Answer 11

When there is a small set of values

Question 12

What does a bubble sort entail?

Answer 12

Iterating through the set n-1 times and comparing a value to the ones which are next to it, if they need to switch a switch is carried out

Question 13

What does a linear search entail?

Answer 13

Iterating through the items in the list and comparing them to the desired item, if they match then this item is returned

Question 14

What does a binary search entail?

Answer 14

Splitting the set in two and then checking to see if the desired item is higher or lower, if it is lower the higher section of the set can be discarded and vice versa. This is repeated until the desired item is attained

Question 15

Why do we test?

Answer 15

To reveal errors and prove that a system does not work

Question 16

Define module testing

Answer 16

Ensuring a subprogram works correctly

Question 17

Define program testing

Answer 17

Ensuring that each program within the system works in isolation

Question 18

Define system testing

Answer 18

Ensuring that the whole system works and does what is required of it according to the specification

Question 19

Why do programmers use testing plans?

Answer 19

To keep track of the result of tests and what parts of the system are/aren’t working

Question 20

Define normal data

Answer 20

Data which the system should accept without any issue

Question 21

Define boundary data

Answer 21

Data which is acceptable but sits either end of the range

Question 22

Define erroneous data

Answer 22

Data which the system should not accept

Question 23

How can trace table be useful to test an algorithm?

Answer 23

By tracing an algorithm you can test the predicted or actual outcome of the system at different stages during the program without implementation

Question 24

Define abstraction

Answer 24

Identifying the difference between information that is relevant to the problem and that which is not and discarding what is not relevant

Question 25

Define information hiding

Answer 25

The process of hiding all details of an object that do not contribute to its essential characteristics

Question 26

Give an example of information hiding

Answer 26

The London Underground Map

Question 27

What is the link between high level languages and abstraction?

Answer 27

High level languages employ abstraction by ensuring that programmers only need to focus on what the computer is doing rather than how it is doing it, this contrasts with machine code

Question 28

Define decomposition

Answer 28

Breaking down a problem into smaller sub-problems so that each sub-problem can be solved to accomplish an identifiable task

Question 29

Define composition

Answer 29

Combining procedures which accomplish individual tasks to form a compound system which accomplishes the overall task

Question 30

What is a finite state machine?

Answer 30

An abstract representation of how a system changes from one state to another in response to an external stimuli

Question 31

What are the three main rules regarding finite state machines?

Answer 31

1. They can only be in one state at a time 2. It switches between states in response to an event of condition (this is called a transition) 3. A finite state machine is defined by a list of states and conditions for each transition

Question 32

Define representational abstraction

Answer 32

The process of removing unnecessary details so that only information that is required to solve the problem remains and the problem is in a state that can be solved

Question 33

Define abstraction by generalisation

Answer 33

The concept of reducing problems by putting similar aspects of a problem into hierarchical categories

Question 34

Define problem solving

Answer 34

The process of finding a solution to real-life problems

Question 35

Define automation

Answer 35

Creating a computer model of a real-life situation and putting it into action

Question 36

Define logical reasoning

Answer 36

The process of using a given set of facts to determine whether new facts are true or false

Question 37

What does hand-tracing/dry running mean?

Answer 37

To follow a program through line by line to determine what is happening and identify problems before it is run

Question 38

Give an example of abstraction by generalisation

Answer 38

Top down diagrams

Question 39

Define top down diagram

Answer 39

Related to the modular approach to problem solving and is a diagram that starts with the main system at the top and breaks it down into smaller and smaller units

Question 40

Define procedural abstraction

Answer 40

The concept that all solutions can be broken down into a series of procedures that can be executed one by one

Question 41

Define functional abstraction

Answer 41

Breaking down a complex problem into a series of reusable functions

Question 42

Define data abstraction

Answer 42

Hiding how data is represented so that it is easier to build a new kind of data object

Question 43

Why is data abstraction beneficial for programmers?

Answer 43

Programmers can utilise the functions of data types without needing to know how they work

Question 44

Define data composition

Answer 44

The process of combining data objects to create a compound structure

Question 45

Define problem abstraction

Answer 45

Removing unnecessary details from a problem until the underlying problem is one that has already been solved

Question 46

How are encapsulation and information hiding linked?

Answer 46

Encapsulation involves grouping data and methods together in classes which means hiding irrelevant information from other parts of the program