Understanding Selection Sort and Bubble Sort

Selection Sort and Bubble Sort are two easy ways to sort things. You might learn about these methods in Year 7 Computer Science class.

Comparing Efficiency:

• Time Complexity:

  • Selection Sort: Takes about $O(n^2)$ time.
  • Bubble Sort: Also takes $O(n^2)$ time when things are not sorted. If the data is already sorted, it can take $O(n)$ time, which is faster.

• Number of Comparisons:

  • Selection Sort: Looks at the data about $(n-1) + (n-2) + ... + 1$ times. That's around $\frac{n(n-1)}{2}$ comparisons total.
  • Bubble Sort: It usually also looks at the data about $\frac{n(n-1)}{2}$ times in the worst case. However, it often makes more swaps.

Conclusion:

In general, Selection Sort is better at fewer swaps, making it more efficient. On the other hand, Bubble Sort can be faster when the data is almost sorted.