Question

Which sort, bubble sort or selection sort, would require fewer passes to sort a set of data that is already in the desired order?

Short answer

Answer: Bubble sort requires fewer passes to sort a dataset that is already in the desired order, as it only needs one pass to recognize that no swaps are needed and it terminates early.

Step-by-step solution

Understanding Bubble Sort

Bubble sort is a simple sorting algorithm that works by repeatedly swapping adjacent elements if they are in the wrong order. The algorithm compares each pair of adjacent elements in the dataset and swaps them if needed. This process is repeated until no more swaps are needed.

Understanding Selection Sort

Selection sort is another simple sorting algorithm that works by dividing the dataset into two parts: the sorted part and the unsorted part. Initially, the sorted part is empty, and the unsorted part contains all the elements. The smallest element from the unsorted part is found and swapped with the leftmost unsorted element. This process is repeated until the entire dataset is sorted.

Comparing Bubble Sort and Selection Sort on Already Sorted Data

Let's apply each sorting algorithm on an already sorted dataset: 1. Bubble Sort: - In the first pass, bubble sort compares each pair of adjacent elements, but since the dataset is already sorted, no swaps are needed. The algorithm then repeats the process, but since no swaps were made in the previous pass, bubble sort terminates knowing that the dataset is already sorted. 2. Selection Sort: - In the first iteration, selection sort identifies the minimum element and swaps it with the leftmost unsorted element. In our case, since the dataset is already sorted, the minimum element is the leftmost element, which means no swaps are needed in the first iteration. However, selection sort proceeds with the next iteration, regardless of whether a swap occurred or not.

Conclusion

For a dataset that is already in the desired order, bubble sort would require fewer passes to sort since it only needs one pass to recognize that no swaps are needed and it terminates early. On the other hand, selection sort would go through all its iterations without considering the state of the dataset.