Bubble Sort

The BubbleSort compares each successive pair of elements in an unordered list and inverts the elements if they are not in order.

The following example illustrates the bubble sort on the list {6,5,3,1,8,7,2,4} (pairs that were compared in each step are encapsulated in ‘**’):

{6,5,3,1,8,7,2,4}
{**5,6**,3,1,8,7,2,4} -- 5 < 6 -> swap
{5,**3,6**,1,8,7,2,4} -- 3 < 6 -> swap
{5,3,**1,6**,8,7,2,4} -- 1 < 6 -> swap
{5,3,1,**6,8**,7,2,4} -- 8 > 6 -> no swap
{5,3,1,6,**7,8**,2,4} -- 7 < 8 -> swap
{5,3,1,6,7,**2,8**,4} -- 2 < 8 -> swap
{5,3,1,6,7,2,**4,8**} -- 4 < 8 -> swap

After one iteration through the list, we have {5,3,1,6,7,2,4,8}. Note that the greatest unsorted value in the array (8 in this case) will always reach its final position. Thus, to be sure the list is sorted we must iterate n-1 times for lists of length n.

Graphic: