2.1 – Algorithms

Question 1

What is abstraction?

Answer 1

• Removing unnecessary details and including only the relevant ones
• Focuses on what is important in problem solving

Question 2

What is decomposition?

Answer 2

• Breaking down a complex problem into small, more manageable parts
• Makes problems easier to solve & different people can work on different parts of a problem at the same time

Question 3

What is algorithmic thinking?

Answer 3

• Getting to a solution by identifying the steps needed
• Creates a set of rules you can follow to lead to an answer
• Can allow a solution to be automated

Question 4

What is an algoritm?

Answer 4

A sequence of steps designed to perform a particular task

Question 5

What is an input?

Answer 5

Data that is entered into or received by a computer

Question 6

What is a process?

Answer 6

A program that is running in a computer

Question 7

What is an output?

Answer 7

How to computer presents the result of a process

Question 8

What is a flow diagram?

Answer 8

A method of designing algorithms before coding using symbols

Question 9

What is a structure diagram?

Answer 9

A diagram that illustrates problem decomposition, produced using a method known as step-wise refinement

Question 10

How do structure diagrams work?

Answer 10

• Decompose the problem; some areas will need more breaking down than others
• Lowest level nodes should achieve a single task which can then be coded as a single module or sub-program

Question 11

What is Pseudocode?

Answer 11

An alternative, text-based way of representing the sequence of steps in an algorithm (simplified programming code)
Has no defined syntax so cannot be compiled or interpreted by the computer

Question 12

What does Pseudocode do?

Answer 12

Lays down the logic of a program in an almost “real code” way without worrying about actual rules & syntax or an actual language

Question 13

What is a Binary Search?

Answer 13

Accessing the middle record and determining whether the data item has been found
If not, checking whether it is before or after the current record in the data set
Discarding the half of the data set that does not contain the record in each pass
Repeating the algorithm until the data item is found or it is not in the data set
It only works if records in the file are in sequence

Question 14

What is a Bubble Sort?

Answer 14

Repeatedly steps through a data set comparing each pair of adjacent items
Swaps pairs of items if they are in the wrong order
Stops when no swaps are made

Question 15

What is an Insertion Sort?

Answer 15

Finds the correct location in a list for an item…
…By comparing it to the other items in the list in a linear way…
…Inserting the new item at the correct position…
…By moving all the other items after it by one index

Question 16

What is a Linear Search?

Answer 16

Examining each data item in turn, starting from index number 0, until the item is found or the end of the data structure / file is reached

Question 17

What is a Merge Sort?

Answer 17

A divide and conquer algorithm
A list is repeatedly divided into smaller lists eventually containing just one item.
Each element is compared with the adjacent list…
…And merged back together from two lists into one