Cormen Edition 3 Exercise 7.1 Question 4 (Page No. 174)

Question

QUICKSORT(A,p,r)
1    if p < r
2    q = PARTITION(A,p,r)
3    QUICKSORT(A, p , q-1)
4    QUICKSORT(A, q + 1, r)

How would you modify QUICKSORT to sort into nonincreasing order?

Answer 1

If you observe PARTITION of the array algorithm carefully then you'll observe at line 4 i.e. in 

$if   A[j]\leq x$

simply the change it to $\leqslant$ which is

$if A[j]\geqslant x$

this will make all the elements greater than pivot move to the left of the array and rest to the right which is the desired result.