public class Node { Node left; Node right; int data; Node( int d ) { this( d, null, null ); } Node( int d, Node l, Node r ) { data = d; left = l; right = r; } void addLeftChild( Node n ) { left = n; } void addLeftChild( int d ) { left = new Node( d ); } void addRightChild( Node n ) { right = n; } void addRightChild( int d ) { right = new Node( d ); } }