Question

Question 5 (10 points) Below is the PARTITION(A, p. r) pseudocode where pivot is always selected as the last element and array A=(-23,7,-14,1,5,1). a. Illustrate the PARTITIONCA, P.7) module operation like below when call it with the above array A. Show clearly the position of i and ; in each picture. Pj PARTITIONCA, p,r) 1. x=A[r] 2. i=p - 1 3. for j =p tor-1 4. if Allsx 5. i=i+1 exchange A[i] with AD 7. exchange A[i+1] with 4[r] 8. return 1+1 6. b. Rewrite PARTITION , P.) module above so that pivot element is always the floor of (pt/2. Illustrate your modified PARTITIONA, P.) module operation like above when call it with the above array A. Show clearly the position of i andſ in each picture.

Answer 1

b) algorithm

  

partition(A,p,r)
i =p
j =r
x = (p+r) / 2

while i <= j

while A[i] < x

i=i+1

while A[j] > x

j=j-1

if i <= j

Excange A[i] with A[j]

i=i+1

j=j-1

return i