Java, calculating complexity

Question

I am trying to calculate complexity of a recursion method inside another methos in a simple while loop.

I dont know how to asnwer this question, I think To just apply the answer O(N*Y) while Y stands for the tree on the recursion.

Tree recursion that gets the number of leafs that bigger Than x:

public static int bigger(BinaryNode<Integer> t, int x)
{
 if(t==null)
 {
 return 0;
 }
 if (t.getValue()>x) {
 return 1;
 }
 return bigger(t.getLeft(),x) + bigger(t.getRight(),x);
}

This is the Method I need to calculate the Complexity for(uses Bigger() in each iteration):

public static Stack<Item> bigInTree(BinaryNode<Integer> bt,Stack<Integer> s) {
 Stack<Item> n = new Stack<>();
 while (!s.isEmpty())
 {
 n.push(new Item(s.top(),bigger(bt,s.top())));
 s.pop();
 }
 return n;
}

Is it O(N^2) or can i simply call it O(N*Y) (Y= number of leafs on t)

Let me know what you think

• Michael: O(Number of elements in the tree * Number of the elements in the stack). You can give those things whatever identifiers you want. e.g. O(N*M)
• itamar nahum: Thank you so much! I just needed someone to confirm♥