3.1 Algorithms

Question 1

What is an algorithm?

Answer 1

A set of instructions to complete a task

Question 2

What is decomposition?

Answer 2

Breaking down problems into sub problems until each sub problem can be solved separately

Question 3

What is Pseudocode and its benefits?

Answer 3

-Pseudocode is a way of writing code in plain English
-Pseudocode can be translated into all other coding languages
-It can be easy to understand

Question 4

What are terminators in a flowchart and what shape is it?

Answer 4

-A start or end
-It is oval shaped

Question 5

What is an input/output in flowchart and what shape is it?

Answer 5

-Where a flowchart is inputting information or outputting it back to the user
-It is a parallelogram shape
-writeline and readline in VB
-OUTPUT and USERINPUT in Pseudocode

Question 6

Which shape represents a process happening in a flowchart?

Answer 6

Rectangle

Question 7

What is:
IF THEN…
…ELSE

Answer 7

-Form of selection
-If a certain condition is met, this code will run otherwise it will not
-logical test

Question 8

What is:
WHILE…
…ENDWHILE

Answer 8

-Indefinite iteration
-Code is repeated until a condition is met
-Checks the condition before the code inside is executed

Question 9

What is:
REPEAT…
…UNTIL

Answer 9

-Indefinite iteration
-Code is repeated until a condition is met
-Checks the condition after the code inside is executed

Question 10

What is:
FOR…
…ENDFOR

Answer 10

-Definite Iteration
-Repeats the code a set number of times

Question 11

What is USERINPUT?

Answer 11

What the user types in

Question 12

What is OUTPUT?

Answer 12

What the computer displays onto the screen

Question 13

What does this symbol mean?
+

Answer 13

Addition

Question 14

What does this symbol mean? -

Answer 14

Subtration

Question 15

What does this symbol mean?
*

Answer 15

Multiplication

Question 16

What does this symbol mean?
/

Answer 16

Division

Question 17

What does this symbol mean? ^

Answer 17

-Carrot
-Used for indices

Question 18

What is DIV?

Answer 18

-Division which only returns the integer
- 9 DIV 2 = 8
- \ in VB

Question 19

What is MOD?

Answer 19

-Division which only returns the remainder
-9 MOD 2 = 1
-Modulas

Question 20

What does this symbol mean? =

Answer 20

Equal to

Question 21

What does this symbol mean?
>

Answer 21

Greater than

Question 22

What does this symbol mean?
<

Answer 22

Less than

Question 23

What does this symbol mean?
≥ in Pseudocode
>= in VB

Answer 23

Greater than or equal to

Question 24

What does this symbol mean?
≤ in Pseudocode
=< in VB

Answer 24

Less than or equal to

Question 25

What does this symbol mean? ≠ in Pseudocode <> in VB

Answer 25

Not equal to

Question 26

What is nested iteration?

Answer 26

In a nutshell: iteration inside of iteration

Question 27

What is meant by casting?

Answer 27

Changing from one data type to another

Question 28

What is INT_TO_STRING?

Answer 28

-Casting -Used in Pseudocode, not VB -Integer to string

Question 29

What is STRING_TO_INT?

Answer 29

-Casting -Used in Pseudocode, not VB -String to Integer

Question 30

What is an integer?

Answer 30

A whole number

Question 31

What is a real / float?

Answer 31

A decimal

Question 32

What is a string?

Answer 32

A sequence of characters

Question 33

What is a character?

Answer 33

-One character is one letter / digit / special character -Any press on the keyboard -A character is one byte

Question 34

What is a boolean?

Answer 34

True or False

Question 35

What is a binary search?

Answer 35

A binary search finds the midpoint of a list in ascending order and checks if the value it is looking for is in that half or not and deletes the half of which it isn't in.

Question 36

What are pros and cons of a binary search?

Answer 36

PRO: It is much more efficient than a binary search CON: -It has to be in order (i.e. numerical or alphabetical) -It is hard to code

Question 37

How is the middle number found in a binary seach?

Answer 37

(n + 1) DIV 2

Question 38

What is a linear search

Answer 38

Searches through the list one item at a time

Question 39

What are the pros and cons of a linear search?

Answer 39

PRO: -The list can be ordered in any way -Easy to code CON: It isn't at all efficient

Question 40

How do you find the maximum number of searches needed in a binary search?

Answer 40

2^n + 1

Question 41

How does a bubble sort work?

Answer 41

-It checks the first two numbers, if the first number is larger than the second it swaps; otherwise it doesn't -At the end of the pass, the largest number is left on the far right -This is repeated until the items have been sorted

Question 42

How do you work out how many passes the bubble sort will need?

Answer 42

(amount of items on the list) - 1

Question 43

How does a merge sort work?

Answer 43

-Keeps splitting the list in half until the numbers are left individually -Merges the numbers back together but in order

Question 44

How are two numbers/lists merged?

Answer 44

-Checks the first number from each list -The smaller one is put first -Checks the second number from the list which was the one with the smaller number in it -Repeats until the lists are merged

Question 45

What are the pros and cons of a merge sort?

Answer 45

PRO - faster than a bubble sort on longer lists CON - Uses more memory - Harder to code than a bubble sort

Question 46

What are the pros and cons of a bubble sort?

Answer 46

PRO - Easier to code than a merge sort CON - Less efficient than a merge sort

Question 47

What is the point of a merge or binary search?

Answer 47

To get the list into order so you can do binary searches on it