What is the running time of QUICKSORT when all elements of array \(A\) have the same value?

This case represents a worst-case scenario for the running of QUICKSORT because the \(A[p..q-1]\) will always contain all the found elements, while the \(A[q+1..r]\) partition will be empty. The runtime in this case is \(\Theta(n^2)\) as outlined in the text.