Observing quadratic behavior with quicksort - O(n^2)

Question

The quicksort algorithm has an average time complexity of O(n*log(n)) and a worst case complexity of O(n^2).

Assuming some variant of Hoare’s quicksort algorithm, wh

Answer 1

To expand on what Bragboy said, instead of only running:

quicksort(array);

Run:

shuffle(array);
quicksort(array);

Where the definition of shuffle() could be:

shuffle(array){
    for(int i = array.length; i > 0; i--){
        r= random number % i;
        swap(array[i], array[r]);
    }
}

Doing so will, likely, deal with the case of getting input which makes quicksort() slow.