Efficiency of Bubble vs. Selection Sort

Question

I understand that the big O values for Bubble Sort and Selection Sort are the same, (n)^2, but when I try to run both with an array of size 1000, the Bubble Sort takes 962037 sw

Answer 1

The Big O notation provides the asymptomatic cost, however, all additive values and constants are omitted. In addition, for a realistic comparison for small numbers, you need to look at the average number of comparisons. More specifically, Bubble sort requires, on average, n/4 swaps per entry , while Selection sort requires only 1, see this post for further details. The number of comparisons will also depend on the initial distribution, for example whether the data is semi-sorted or completely random.