The.Algorithm.Design.Manual.Springer-Verlag.1998

Randomization
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Randomization
Suppose we select, at random, one of the n items we seek to sort. Call this element p. In quicksort, we
separate the n-1 other items into two piles: a low pile containing all the elements that will appear before p
in sorted order and a high pile containing all the elements that will appear after p in sorted order. After
sorting the two piles and arranging the piles correctly, we have succeeded in sorting the n items.
Quicksort(A, low, high)
Partition(A,low,high)
if (low < high)
ploc = Partition(A,low,high)
Quicksort(A,low, ploc - 1)
Quicksort(A, ploc+1, high)
swap(A[low],A[random( )])
pivot = A[low]
leftwall = low
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