Bubble Sort The bubble sort is the simplest sorting algorithm. It compares adjacent items and exchanges those that are out of order. With each pass though the list of items, an item appears to 'bubble up' to the location where it belongs. How many items in the list_? What items are exchanged (swapped) first? You can add numbers separated by a comma or a space: 12,3 or 123 What items are exchanged the last? How many exchanges were done?.