# Which sorting algorithm is best in worst case?

## Which sorting algorithm is best in worst case?

Quicksort is usually the fastest, but if you want good worst-case time, try Heapsort or Mergesort. These both have O(n log n) worst time performance.

## What is the order of quick sort in the worst case?

Mathematical analysis of quicksort shows that, on average, the algorithm takes O(n log n) comparisons to sort n items. In the worst case, it makes O(n2) comparisons.

How heap sort is different from merge sort?

One issue is that heap sort swaps data, that’s two reads and two writes per swap, while merge sort moves data, one read and one write per move.

What is the best case time complexity of merge sort *?

Sorting algorithms

Algorithm Data structure Time complexity:Best
Quick sort Array O(n log(n))
Merge sort Array O(n log(n))
Heap sort Array O(n log(n))
Smooth sort Array O(n)

### What sorting algorithms have their best and worst case times equal?

Time Complexities of all Sorting Algorithms

Algorithm Time Complexity
Best Worst
Heap Sort Ω(n log(n)) O(n log(n))
Quick Sort Ω(n log(n)) O(n^2)
Merge Sort Ω(n log(n)) O(n log(n))

### Which of the following algorithms has the lowest best and worst case complexity?

Answer is C. Worst case complexity of merge sort is O(nlogn).

Which of the following statements represent the worst case input for QuickSort?

Explanation: The worst case performance of a quick sort algorithm is mathematically found to be O(N2).

What is the difference between Quicksort and heap sort?

Heapsort is typically somewhat slower than quicksort, but the worst-case running time is always Θ(nlogn). Quicksort is usually faster, though there remains the chance of worst case performance except in the introsort variant, which switches to heapsort when a bad case is detected.

#### What is difference between Quicksort and Merge Sort?

The main difference between quicksort and merge sort is that the quicksort sorts the elements by comparing each element with an element called a pivot while merge sort divides the array into two subarrays again and again until one element is left. Sorting is the method of arranging data in a particular order.

#### What is the recurrence relation for merge sort?

In merge sort, we divide the array into two (nearly) equal halves and solve them recursively using merge sort only. Finally, we merge these two sub arrays using merge procedure which takes Θ(n) time as explained above. On solving this recurrence relation, we get T(n) = Θ(nlogn).

What is the worst case for merge sort?

In the worst case, merge sort does about 39% fewer comparisons than quicksort does in the average case. In terms of moves, merge sort’s worst case complexity is O(n log n)—the same complexity as quicksort’s best case, and merge sort’s best case takes about half as many iterations as the worst case.

Why is quicksort better than mergesort?

Quicksort usually is better than mergesort for two reasons: Quicksort has better locality of reference than mergesort, which means that the accesses performed in quicksort are usually faster than the corresponding accesses in mergesort.