Which of the following sorting algorithm has best case time complexity of O(n2)? ans. insertion sort stupid sort bubble sort selection sort

All of the mentioned sorting algorithms - insertion sort, stupid sort, bubble sort, and selection sort - have a best case time complexity of O(n^2).

Here's a brief explanation of each:

1. Insertion Sort: This algorithm works by dividing the array into a sorted and an unsorted region. The numbers are then inserted into their correct position in the sorted region. The best case time complexity is O(n), but the average and worst case time complexity is O(n^2).

2. Stupid Sort (also known as Bogosort): This is a highly inefficient sorting algorithm that randomly generates permutations of its input until it finds one that is sorted. It has a worst-case time complexity of O((n+1)!), and a best-case time complexity of O(n).

3. Bubble Sort: This algorithm repeatedly steps through the list, compares adjacent elements and swaps them if they are in the wrong order. The pass through the list is repeated until the list is sorted. The average and worst case time complexity is O(n^2).

4. Selection Sort: This algorithm sorts an array by repeatedly finding the minimum element from unsorted part and putting it at the beginning. The average and worst case time complexity is O(n^2).

So, all of these sorting algorithms have a best case time complexity of O(n^2), except for Insertion Sort which has a best case time complexity of O(n) and Stupid Sort which has a best case time complexity of O(n).