Trace the execution of quicksort on the following array, assuming that the first item in each subarray is the pivot value.

Show the values of first and last for each recursive call and the array elements after returning from each call.

Show the value of pivot during each call and the value returned through pivIndex.

How many times is sort called, and how many times is partition called?

55 50 10 40 80 90 60 100 70 80 20 50 22