Algorithms Sorting & Searching Algorithms

Question 1

What is the average-case time complexity of QuickSort?

Accepted Answer

O(n log n)

Answer

QuickSort achieves O(n log n) average-case complexity by recursively partitioning the array around a pivot element.

Question 2

Which sorting algorithm is considered stable and has a guaranteed worst-case time complexity of O(n log n)?

Accepted Answer

MergeSort

Answer

MergeSort is stable and guarantees O(n log n) in all cases by dividing the array into halves and merging them in sorted order.

Question 3

What is the time complexity of Binary Search on a sorted array of n elements?

Accepted Answer

O(log n)

Answer

Binary Search eliminates half the remaining elements at each step, yielding O(log n) time complexity.

Question 4

Which sorting algorithm has the best performance on nearly sorted data?

Accepted Answer

Insertion Sort

Answer

Insertion Sort runs in O(n) time on nearly sorted data because few elements need to be moved.

Question 5

What is the worst-case time complexity of Bubble Sort?

Accepted Answer

O(n²)

Answer

Bubble Sort has O(n²) worst-case complexity because it compares adjacent pairs across n passes of the array.

Algorithms Practice Test