Quicksort
Usually the quicksort will run faster than
the mergesort...
but if you are dealing with already sorted or
mostly sorted data, you will get worst case
performance out of the quicksort which will be
significantly slower than the mergesort.
with an array that is already sorted in ascending
order and the pivot is always the smallest
element in the array, then there are N-1
comparisons for N elements in your array.