@arjun sir if they ask about best case the we take always those input which gives us best case then in the above question if i take input 18, 19,17,11,12,15,16, 9,10,7,6,13,14,12 ,11 if u draw it then u find that it is a complete binary tree as well as right and left subtree of root are max heap . i m taking this case bcz i m intresed to find out best case complexity then here they take 2 comparision and swaping whcih takes O(1) time bt they did not mention this into option so take a case as mention by anirudh so here get O(logn) is it correct ??