資料結構與演算法(A)

(5 points) When CAN the worst case of Quicksort occur?

• $C_1$: Quick Sort where leftmost (or rightmost) element is always chosen as pivot
• $C_2$: leftmost element is chosen as pivot and array is already sorted in SAME order
• $C_3$: leftmost element is chosen as pivot and array is already sorted in REVERSE order