Algorithms

Question 1

What is abstraction?

Answer 1

Hiding or removing unnecessary data to keep something simple

Question 2

What is decomposition?

Answer 2

Breaking down a problem into smaller subproblems

Question 3

What is algorithmic thinking?

Answer 3

Identifying the steps involved in solving a problem

Question 4

What symbol is used to represent an input in a flow chart?

Answer 4

Parallelogram

Question 5

What symbol is used to represent an output in a flow chart?

Answer 5

Parallelogram

Question 6

What symbol is used to represent a decision in a flow chart?

Answer 6

Rhombus

Question 7

What symbol is used to represent a process in a flow chart?

Answer 7

Rectangle

Question 8

What symbol is used to represent a terminal in a flow chart?

Answer 8

Oval

Question 9

What symbol is used to represent a subroutine in a flow chart?

Answer 9

Rectangle with two vertical lines near each end of the shape

Question 10

What is used to connect each symbol in a flow chart?

Answer 10

An arrow

Question 11

Name two examples of decomposition

Answer 11

• Flow charts
• Structure diagrams

Question 12

What is a structure diagram?

Answer 12

A way of visually showing the breakdown of a program into individual steps (subroutines)

Question 13

What are trace tables?

Answer 13

Tables used in testing that show every variable change in a program

Question 14

When would you use a trace table?

Answer 14

• When testing
• When checking for logic errors

Question 15

What is a syntax error?

Answer 15

An error that will prevent the code from executing

Question 16

What is a logic error?

Answer 16

An error that will still allow a program to run, but it won’t work as intended

Question 17

What are the 2 types of searching algorithm?

Answer 17

• Binary search
• Linear search

Question 18

What are the 3 types of sorting algorithm?

Answer 18

• Bubble sort
• Merge sort
• Insertion sort

Question 19

Why would you use a linear search over a binary search?

Answer 19

The list doesn’t need to be ordered

Question 20

Why would you use a binary search over a linear search?

Answer 20

Because it is usually quicker

Question 21

How does a linear search work?

Answer 21

Each element in the list is checked in order until the correct one is found

Question 22

How does a binary search work?

Answer 22

• The midpoint of the list is checked
• If the value is higher than the element being searched for the middle element and all greater than it are discarded
• Otherwise the midpoint and all elements bellow it are discarded
• This happens until the desired element is found

Question 23

How do you find the midpoint of a list?

Answer 23

Add the two end points (the element number, not the value) and divide them by 2

Question 24

Which is the most efficient sorting algorithm?

Answer 24

Merge sort

Question 25

Which is the least efficient sorting algorithm?

Answer 25

Bubble sort

Question 26

How does a bubble sort work?

Answer 26

• During each pass the first two elements are checked and if in the wrong order is swapped, then the next two elements are checked
• Passes happen until one pass results in no swapping

Question 27

How does a merge sort work?

Answer 27

• The list is divided into individual elements
• Each element is ordered in a sublist with the one next to it
• The sublists merge whilst being ordered until there is only one list

Question 28

What is computational thinking?

Answer 28

The use of computers to solve a problem