Bubble Sort (AQA GCSE Computer Science)

Bubble Sort

What is a bubble sort?

• A bubble sort is a simple sorting algorithm that starts at the beginning of a dataset and checks values in 'pairs' and swaps them if they are not in the correct order

• One full run of comparisons from beginning to end is called a 'pass', a bubble sort may require multiple 'passes' to sort the dataset

• The algorithm is finished when there are no more swaps to make

How do you perform a bubble sort?

Example

• Perform a bubble sort on the following dataset

A bubble sort in python

# unsorted dataset
nums=[66, 7, 69, 50, 42, 80, 71, 321, 67, 8, 39]

# count the length of the dataset
numlength = len(nums)

# sets a flag to initiate the loop
swaps = True

while swaps == True : 
    swaps = False
    # loop through the dataset
    for y in range(numlength-1) :
        # if the first number is bigger than the second number
        if nums[y] > nums[y+1] :
            # swap the numbers using a temporary variable
            temp = nums[y]
            nums[y] = nums[y+1]
            nums[y+1] = temp
            # sets the flag to true
            swaps = True

# prints the sorted list
print (nums)