BT15.java

public class BT15 {

    static class Node {

        int data;
        Node right;
        Node left;

        Node(int data) {
            this.data = data;
            this.left = null;
            this.right = null;
        }
    }

    static int KthAncestor(Node root, int n, int k) {
        if (root == null) {
            return -1;
        }
        if (root.data == n) {
            return 0;
        }
        int left = KthAncestor(root.left, n, k);
        int right = KthAncestor(root.right, n, k);
        if (left == -1 && right == -1) {
            return -1;
        }
        int max = Math.max(left, right);
        if (max + 1 == k) {
            System.out.println("Kth Ancestor is: " + root.data);
        }
        return max + 1;

    }

    public static void main(String[] args) {

        Node root = new Node(1);
        root.left = new Node(2);
        root.right = new Node(3);
        root.left.left = new Node(4);
        root.left.right = new Node(5);
        root.right.left = new Node(6);
        root.right.right = new Node(7);
        System.out.println(KthAncestor(root, 6, 2));

    }

}