Sorting algorithms (Y11)

What is a sorting algorithm?

• Specific instructions which allow us to understand code

• Specific instructions which allow us to organise data in a particular way

• Kinda like a word-scrambler

• Kinda like a password-decrypter

What is the most important reason that data needs to be sorted?

• It is organised and easier to make sense of.

• So it looks nice.

• To show we can do it.

Which of the following are sorting algorithms?

• Binary, linear

• Numerical, phonetic

• Bubble, merge

• File, alphabetical

How do bubble sorts work?

• They split the list to single elements before piecing them back together, one sublist at a time.

• Each item in the list is compared with the following item starting with the last value till the first.

• Taking one item at a time from an unsorted list, each new item is compared with the previous until its place is found.

• Each item in the list is individually compared with the following item starting with the first value till the last.

What is an advantage of a bubble sort?

• It is difficult to implement.

• It is fast.

• It uses less memory.

• It is easier to implement and follow.

What is the maximum number of comparisons if there are 5 elements to sort?

• 10
• 2
• 5
• 20

How do you calculate the maximum number of passes/iterations? Where n = number of elements in a list.

• n - 1

• n + 1

• n(n+1)

• n(n-1)

How many passes are required to sort a list with 5 elements?

• 5

• 4

• 10

• 2

The following list is to be sorted using a bubble sort:

12 6 8 1 3

What will the list look like after the first iteration/run through the list?

• 6 8 1 3 12

• 6 12 1 8 3

• 1 3 6 8 12

• 6 8 1 12 3

Why does a bubble sort do a final pass even when the data is in the correct order?

• To save the data.

• It does not recognise that the data is in order until the final pass requires no changes.

• It needs to do this to put the data back in to a list.

• To annoy the user.