2.1 Algorithms

Question 1

What is an algorithm?

Answer 1

A sequence of step-by-step instructions to solve a problem or carry out a task. Can be represented using a flowchart or pseudocode.

Question 2

What is a program?

Answer 2

A sequence of instructions for a computer.

Question 3

What is computational thinking?

Answer 3

Solving problems logically, in a way that can be understood by humans and computers.

Question 4

What is abstraction?

Answer 4

The removal of unwanted or unnecessary information from a task or problem in order to focus on the important and relevant information.

Question 5

What is decomposition?

Answer 5

The process of breaking larger problem down into smaller tasks into smaller tasks that are easier to understand and solve.

Question 6

What is sequence?

Answer 6

Carrying out tasks in a step-by-step series

Question 7

What is iteration?

Answer 7

Repeating a task until a certain condition is met

Question 8

What is selection?

Answer 8

A decision that needs to be made before the next step can be carried out.

Question 9

What is a binary search?

Answer 9

Compares the required item to middle of the list, discards the irrelevant half of the list, repeats until the required item is found or the list has been fully checked.

Question 10

Advantages and Disadvantages of binary search

Answer 10

+ Fast/efficient

• Only works in an ordered list
• Only works with numbers

Question 11

What is a linear search?

Answer 11

compares each value in a list, one at a time, to a required value until a match is made.

Question 12

Advantages and Disadvantages of linear search

Answer 12

+ Works with an unordered list

- Slower/less efficient than other searching algorithms

Question 13

What is a bubble sort?

Answer 13

Repeatedly compares adjacent pairs of values in a list and swaps until all items are in order.

Question 14

Advantages and Disadvantages of bubble sort

Answer 14

+ Simple algorithm and can be easily implemented on a computer
+ Doesn’t use much memory
- Doesn’t cope well with large lists
- Slower/less efficient than merge sort

Question 15

What is a merge sort?

Answer 15

Data is repeatedly split into halves until single items remain, and is then reassembled in order.

Question 16

Advantages and Disadvantages of merge sort

Answer 16

+ Quick/efficient

• It’s slower on algorithms for small lists
• Uses more memory than other sorting algorithms

Question 17

What is an insertion sort?

Answer 17

Sorts data one element at a time. The algorithm takes one data from the list and places it in the correct location in the list. This process o=is repeated until there are no more unsorted items in the list.

Question 18

Advantages and Disadvantages of insertion sort

Answer 18

+ Doesn’t use much memory

- Doesn’t cope well with large lists

Question 19

Pseudocode

Answer 19

A shared programming language using simple English terms to plan programs

Question 20

Flowcharts

Answer 20

Visualises an algorithm and shows clearly the flow of information

Question 21

Advantages of flowcharts

Answer 21

• It is easy to see how a program flows. For example, where does following one path as opposed to another take the program?
• Flow diagrams follow an international standard - it’s easy for any flow diagram user to pick up a diagram and understand it.

Question 22

Disadvantages of flowcharts

Answer 22

• with a large program, the diagrams can become huge in size and unwieldy to follow
• any changes to the design may mean a lot of the diagram has to be redrawn