Compared to merge sort, standard quick sort is
Ain-place (O(log n) stack), but NOT stable
Bstable but uses O(n) extra memory
Cstable AND in-place; merge sort is neither
Dunstable and uses O(n) extra memory
Answer & Solution
Correct answer: A. in-place (O(log n) stack), but NOT stable
Quick sort needs only the recursion stack (O(log n) on balanced splits), making it in-place compared to merge sort's O(n) aux array. But its long-range swaps during partition can reorder equal-keyed elements, so it is NOT stable. Merge sort is stable but needs O(n) extra memory. The two algorithms trade memory for stability.
Related questions
An NP-hard problem differs from an NP-complete one because NP-hard problemsThe first problem proved to be NP-complete wasA problem X is NP-complete if and only ifWhy does theoretical computer science draw the line at 'polynomial-time' for tractability?Which set inclusion is established (i.e., proven, not open)?The class NP is the set of decision problems for whichFloyd-Warshall detects the presence of a negative cycle byTopological sort is well-defined for