2.1 - Algorithms

Question 1

What is an algorithm?

Answer 1

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

Question 2

What is algorithmic thinking?

Answer 2

Following logical steps to solve a problem

Question 3

What is abstraction?

Answer 3

Ignoring unnecessary information to simplify a problem

Question 4

What is decomposition?

Answer 4

Breaking down a problem into smaller tasks so it is easier to solve

Question 5

In a flowchart what represents start/stop terminators?

Answer 5

A ‘squircle’ (square-circle) ▢

Question 6

In a flowchart what represents subroutines?

Answer 6

A rectangle with a vertical line either side

Question 7

In a flowchart what is represents the direction of flow?

Answer 7

An arrow

Question 8

In a flowchart what represents an input or output?

Answer 8

A parallelogram

Question 9

In a flowchart what represents a process?

Answer 9

A rectangle

Question 10

In a flowchart what is used to represent a decision?

Answer 10

A diamond with two branches (yes and no)

Question 11

How do you use a trace table?

Answer 11

• Go through every line
• Only add to a column when that column’s value changes
• (Generally) move onto a new row when you move into a new ‘block’ in the code
• Gaps are fine

Question 12

What is a linear search?

Answer 12

Compares each item one by one until the target is found or the end of the list is reached

Question 13

What are the advantages of using a linear search?

Answer 13

• No need for the list to be in order
• Quick process for short lists

Question 13

What is the disadvantage of using a linear search?

Answer 13

Long process for long lists

Question 14

What is a binary search?

Answer 14

• Compares middle item to the target
• Discards half of the list which the target can’t be in
• Finds the next middle item and repeats until the target is found/runs out of items

Question 15

What is the advantage of using a binary search?

Answer 15

Time efficient in a large data set

Question 16

What is the disadvantage of using a binary search:?

Answer 16

Needs to be in order beforehand

Question 17

What is bubble sort?

Answer 17

• In one pass, go through each pair, swapping if needed
• Repeat passes until a pass happens with no swaps

Question 18

What is merge sort?

Answer 18

• Divides the list continuously by two until each list has 1 item
• Combines two lists at a time, keeping the items in order

Question 19

What is insertion sort?

Answer 19

Starts with 1 item in the ‘sorted part’ and moves items one by one from the ‘unsorted part’ to the ‘sorted part’