2.1 Bubble sort

Question 1

bubble sort algorithm

Answer 1

compares adjacent data items and orders them

several passes may be needed to sort the whole list

Question 2

order of sorting

Answer 2

data can be sorted into ascending or descending order

Question 3

how a bubble sort works

Answer 3

• starts at the first two items, if they are not in the correct order they are swapped
• looks at the second and third items, if they are in the correct place they are left alone
• continues until the end of the list
• passes through the list again until none of the items need to be swapped

Question 4

A student has stored the names of some friends in a list

David, Claire, Stefan, Sophie, Matt

Show the stages of a bubble sort when applied to this data to sort it into ascending order [5]

Answer 4

pass 1:
*Claire, *David, Stefan, Sophie, Matt
Claire, David, Stefan, Sophie, Matt
Claire, David, *Sophie, *Stefan, Matt
Claire, David, Sophie, *Matt, *Stefan

pass 2:
Claire, David, *Matt, *Sophie, Stefan

pass 3:
Claire, David, Matt, Sophie, Stefan

Question 5

Show the stages of a bubble sort when applied to the following data to sort it into ascending order:

4, 1, 2, 6, 3, 5 [5]

Answer 5

pass 1:
*1 *4 2 6 3 5
1 *2 *4 6 3 5
1 2 4 6 3 5
1 2 4 *3 *6 5
1 2 4 3 *5 *6

pass 2:
1 2 4 3 5 6
1 2 4 3 5 6
1 2 *3 *4 5 6