2.1 Algorithms STARTED

Question 1

Define linear search

Answer 1

A sequence that checks every item in a list 1 by 1 until it finds the desired item.

Question 2

Define binary search

Answer 2

A sequence that finds the desired item of a list according to the midpoints.

Question 3

What happens if the midpoint is greater than the desired item?

Answer 3

It scraps the midpoint and the data to its left and checks again.

Question 4

What happens if the midpoint is smaller than the desired item?

Answer 4

It scraps the midpoint and the data to its right.

Question 5

Define bubble sort

Answer 5

Bubble sort makes multiple passes through a list. It compares items and changes those that are out of order. Each pass through the list places the next largest value in its proper place.

Question 6

How are numbers sorted in bubble sort?

Answer 6

Compares 1st 2 items and swaps them if necessary.

Question 7

Define pass

Answer 7

A full cycle of swapping (doesn’t mean list is sorted).

Question 8

Define insertion sort

Answer 8

A more efficient version of bubble sort. Each pass would insert each number into its correct place.

Question 9

How are numbers sorted in insertion sort?

Answer 9

Compares 1st 2 items and inserts the necessary item into its complete correct position rather than swapping them. Has 2 lists, unsorted and sorted.

Question 10

Where is insertion sort very efficient?

Answer 10

A small data set or where data is mostly sorted. E.g. a pack of cards.

Question 11

What is merge sort?

Answer 11

An efficient sequence that divides an unsorted list into sublists with 1 item each and merges the lists together until it has a complete sorted list.

Question 12

Define computational thinking

Answer 12

Use of computers to solve problems.

Question 13

Define abstraction

Answer 13

Representing “real world” problems in a computer using variables and symbols and removing unnecessary elements from the problem.

Question 14

Define decomposition

Answer 14

Breaking down a large problems into smaller sub-problems.

Question 15

Define algorithmic thinking

Answer 15

Identifying the steps involved in solving a problem.

Question 16

Computational thinking

Answer 16

Describes the thought processes involved in understanding problems and formulating solutions in such a way that they can be carried out by computers

Question 17

Decomposition

Answer 17

Reduces a problem into sub-problems or components. These smaller parts are easier to understand and solve

Question 18

Decomposition is an example of what type of approach?

Answer 18

Divide-and-conquer

Question 19

Abstraction

Answer 19

Identifies essential elements that must be included in the computer models of real-life situations and discards the inessential ones

Question 20

What is pattern recognition sometimes called?

Answer 20

Generalisation

Question 21

Pattern recognition is used to identify where constructs such as what can be used?

Answer 21

selection and iteration

Question 22

Pattern recognition is used to identify where sections of code can be ______ (functions and procedures)

Answer 22

reused

Question 23

Pattern recognition is used to recognise a problem that is similar to…

Answer 23

one you have solved in the past

Question 24

Pattern recognition is used to reuse code, functions and procedures from past programs to…

Answer 24

carry out similar functions in a new program

Question 25

Algorithmic thinking is a subset of computational thinking that involves...

Answer 25

defining a clear set of instructions to solve a problem

Question 26

With algorithmic thinking, once a successful solution to a problem has been found...

Answer 26

it can be used repeatedly for the same problem

Question 27

The process of adding up all the numbers and diving the total by the number in the set to calculate the mean is an example of...

Answer 27

Algorithmic thinking

Question 28

Algorithms provide instructions needed to...

Answer 28

solve a problem

Question 29

All computer programs are what?

Answer 29

Algorithms

Question 30

An algorithm is a step-by-step procedure for...

Answer 30

solving a problem or carrying out a task

Question 31

How are algorithms often used to improve efficiency?

Answer 31

By removing the need for human input - a computer following an algorithm can do things in split seconds compared to humans

Question 32

What are the three constructs used in an algorithm?

Answer 32

Sequence, selection and iteration

Question 33

Sequence

Answer 33

Instructions need to be given in the correct order

Question 34

Selection

Answer 34

Decisions have to be made and a course of action selected

Question 35

Iteration

Answer 35

Previous steps are repeated until there is a desired outcome

Question 36

Once an algorithm has been written, it can be...

Answer 36

reused with slight changes for solving similar problems

Question 37

Why do we reuse algorithms?

Answer 37

It is much quicker than starting from scratch each time

Question 38

True/False: Algorithms can be displayed using pseudocode

Answer 38

True

Question 39

Pseudocode is a way of expressing an algorithm in...

Answer 39

structured English that resembles a computer language

Question 40

True/False: There is only one way to write pseudocode

Answer 40

False, there are many different varieties of pseudocode

Question 41

Pseudocode uses what similar to those found in computer languages?

Answer 41

Commands, keywords and structures

Question 42

Pseudocode can/cannot be understood by computers

Answer 42

cannot

Question 43

Pseudocode is used to develop the logic of an algorithm without having to bother about what?

Answer 43

syntax

Question 44

A human can/cannot follow the logic of an algorithm even if there are spelling mistakes or missing brackets

Answer 44

can

Question 45

A human can follow the logic of an algorithm even if there are spelling mistakes or missing brackets but a computer...

Answer 45

cannot execute code if there are similar syntax errors

Question 46

A solution in pseudocode is converted into...

Answer 46

a programming language such as Python or Java

Question 47

How can you add comments to code?

Answer 47

// or #

Question 48

Why are comments used in code?

Answer 48

To help others follow programmers' logic, and to act as a reminder of the logic

Question 49

How does indenting help with the logic of an algorithm?

Answer 49

It shows dependency

Question 50

What does this symbol in a flowchart represent?

Answer 50

Start/stop

Question 51

What does this symbol in a flowchart represent?

Answer 51

Input/output

Question 52

What does this symbol in a flowchart represent?

Answer 52

A decision - shows yes/no or true/false decisiopns where there are two possible outcomes

Question 53

What does this symbol in a flowchart represent?

Answer 53

A process - for example a calculation

Question 54

What does this symbol in a flowchart represent?

Answer 54

A subroutine - shows a function or procedure that has its own flow diagram

Question 55

What do lines in flow charts represent?

Answer 55

Control passing between symbols

Question 56

What does the start/stop symbol in a flow chart show?

Answer 56

The start and end of an algorithm

Question 57

What does the input/output symbol in a flowchart show?

Answer 57

Input or output of data

Question 58

What does the decision symbol in a flowchart show?

Answer 58

Yes/no or true/false decisions where there are two possible outcomes

Question 59

What does the process symbol in a flowchart show?

Answer 59

Data processing, for example a calculation

Question 60

What does the subroutine symbol in a flowchart show?

Answer 60

A function or procedure that has its own flow diagram

Question 61

When large amounts of data are searched, it is essential that the searching algorithm is as...

Answer 61

efficient as possible

Question 62

What type of algorithm are linear and binary?

Answer 62

Standard search algorithms