Approach is to store the value of the capacity in some variable whenever the capacity becomes less than zero.

In this case You have to traverse the array only once as compared to previous method which traverses the each index twice.

Traverse the tree in the inorder traversal. If the Binary search tree is traversed in inorder traversal the keys are traversed in increasing order. So while traversing the keys in the inorder traversal. If the key lies in the range print the key else skip the key.

A tricky method is to replace all elements using one traversal of the array. The idea is to start from the rightmost element, move to the left side one by one, and keep track of the maximum element. Replace every element with the maximum element.