Check if a binary tree is subtree of another binary tree

Given two binary trees, check if the first tree is subtree of the second one.

Code:

package trees;

public class N2011_subTree {
   
    Node root1, root2;

    static class Node{
        int data;
        Node left, right;

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

    static boolean isIdentical(Node n1, Node n2){

        if(n1 == null && n2 == null){
            return true;
        }

        if(n1 != null && n2 != null){

            return (n1.data == n2.data) && isIdentical(n1.left, n2.left) && isIdentical(n1.right, n2.right);

        }
       
        return false;
    }
   
    static boolean isSubtree(Node t, Node s){
       
        if(s == null){
            return true;
        }
       
        if( t == null){
            return false;
        }
       
        if( isIdentical(t, s)){
            return true;
        }
       
        return isSubtree(t.left, s) || isSubtree(t.right, s);
       
       
       
    }
   
   


    public static void main(String[] args){
           
        N2011_subTree tree = new N2011_subTree();
       
        // TREE 1
        /* Construct the following tree
              26
             /   \
            10     3
           /    \     \
          4      6      3
           \
            30  */
          
        tree.root1 = new Node(26);
        tree.root1.right = new Node(3);
        tree.root1.right.right = new Node(3);
        tree.root1.left = new Node(10);
        tree.root1.left.left = new Node(4);
        tree.root1.left.left.right = new Node(30);
        tree.root1.left.right = new Node(6);
 
        // TREE 2
        /* Construct the following tree
           10
         /    \
         4      6
          \
          30  */
          
        tree.root2 = new Node(10);
        tree.root2.right = new Node(6);
        tree.root2.left = new Node(4);
        tree.root2.left.right = new Node(30);
 
        if (isSubtree(tree.root1, tree.root2))
            System.out.println("Tree 2 is subtree of Tree 1 ");
        else
            System.out.println("Tree 2 is not a subtree of Tree 1");




    }

}



Output:

Tree 2 is subtree of Tree 1

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