Quicksort

• QUICKSORT(A,left, right)
  
   if left < right
       p ← Partition(A,left,right)
       QUICKSORT(A,left,p)
       QUICKSORT(A,p+1,right)
  
       

• We can use the partition from the last chapter, which was Θ(n)
• Or a partition algorithm on page 178, which might split the array more evenly. (But only in the case of duplicates of the pivot element)
• Terminate?
• Work? (Trace it at least)
• Performance?
• What is the worst case?
  • Randomized quicksort selects a random element to swap with the element in position left then partitions.
  • Or selects the median of the middle, left and right element, to put in position left, then partition.
  • Or a quick check to see if the array is in order.