2023 One way to improve the RANDOMIZED QUICKSORT procedure is to partition around a pivot that is chosen more | Assignment Collections
Computer Science 2023 Median-of-3 Partition
2023 One way to improve the RANDOMIZED QUICKSORT procedure is to partition around a pivot that is chosen more | Assignment Collections
One way to improve the RANDOMIZED-QUICKSORT procedure is to partition around a pivot that is chosen more carefully than by picking a random element from the sub array. One common approach is the median-of-3 method: choose the pivot as the median (middle element) of a set of 3 elements randomly selected from the sub array. (See Exercise 7.4-6.) For this problem, let us assume that the elements in the input array A[1 ? n] are distinct and that n ≥ 3. We denote the sorted output array by A“[1 ? n]. Using the median-of-3 method to choose the pivot element x, define pi = Pr{x = A“[i]}.
a. Give an exact formula for pi as a function of n and i for i = 2, 3,…, n – 1. (Note that p1 = pn = 0.)
b. By what amount have we increased the likelihood of choosing the pivot as x = A”[⌊(n + 1/2⌋], the median of A[1 ? n], compared to the ordinary implementation? Assume that n → ∞, and give the limiting ratio of these probabilities.
c. If we define a “good” split to mean choosing the pivot as x = A“[i], where n/ ≤ i ≤ 2n/3, by what amount have we increased the likelihood of getting a good split compared to the ordinary implementation? (Hint: Approximate the sum by an integral.)
d. Argue that in the Ω(n lg n) running time of quicksort, the median-of-3 method affectsonly the constant factor.
We give our students 100% satisfaction with their assignments, which is one of the most important reasons students prefer us to other helpers. Our professional group and planners have more than ten years of rich experience. The only reason is that we have successfully helped more than 100000 students with their assignments on our inception days. Our expert group has more than 2200 professionals in different topics, and that is not all; we get more than 300 jobs every day more than 90% of the assignment get the conversion for payment.