Height of binary search tree in constant time

Question

I need to fine the height of a binary search tree with a time of O(1) the only way i could think to do this is to put a check in the add and remove methods incrementing a global

Answer 1

O(1) time suggests that you should already have the height when it is requested.

The best way is it to keep/update the correct value whenever a new node is added/deleted . You are doing it in a right way , however it increases the complexity on addition and deletion.

You can do it number of ways , like keep the depth value along with the node in tree etc.

class Node{
int depth;
Object value;
}

Node lowestNode;

I can think of storing the max depth node reference in an object and keep that as depth . So whenever you add a new element , you can check the depth of element based on its parent and replace the max depth node if the new element has more depth .

If you are deleting the max depth node then replace it with the parent otherwise correct the depth of all elments recursively along the tree.

The height of tree is , lowestNode.depth