The Efficiency of Bubble Sort

The Bubble Sort algorithm contains two kinds of steps:

  • Comparisons: two numbers are compared with one another to determine which is greater.

  • Swaps: two numbers are swapped with one another in order to sort them.

Let’s start by determining how many comparisons take place in Bubble Sort.

Our example array has five elements. Looking back, you can see that in our first passthrough, we had to make four comparisons between sets of two numbers.

In our second passthrough, we had to make only three comparisons. This is because we didn’t have to compare the final two numbers, since we knew that the final number was in the correct spot due to the first passthrough.

In our third passthrough, we made two comparisons, and in ...

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