class binary root { static class Node { int data; Node left, right; Node(int data) { this.data = data; left = right = null; } }; static boolean ifNodeExists( Node node, int key) { if (node == null) return false; if (node.data == key) return true; boolean res1 = ifNodeExists(node.left, key); // now recur on right subtree / boolean res2 = ifNodeExists(node.right, key); return res1 || res2; } // Driver Code public static void main(String args[]) { Node root = new Node(0); root.left = new Node(1); root.left.left = new Node(3); root.left.left.left = new Node(7); root.left.right = new Node(4); root.left.right.left = new Node(8); root.left.right.right = new Node(9); root.right = new Node(2); root.right.left = new Node(5); root.right.right = new Node(6); int key = 4; if (ifNodeExists(root, key)) System.out.println("YES"); else System.out.println("NO"); } }