Question Not Clear. 3 TEST CASES PASSED , 1 WRONG ANS

i didn’t understood the question properly. What is meant by “STRUCTURAL IDENTITY” here? I assumed that the given trees are equally balanced / unbalanced. So, I calculated the difference of the difference of the left and right subtrees of the 2 given trees.
CODE:
import java.util.;
import java.lang.
;
public class Main {

static Scanner scn = new Scanner(System.in);

public static void main(String[] args) {
	Main m = new Main();
	BinaryTree bt1 = m.new BinaryTree();
	BinaryTree bt2 = m.new BinaryTree();
	System.out.println(bt1.structurallyIdentical(bt2));
}

private class BinaryTree {
	private class Node {
		int data;
		Node left;
		Node right;
	}

	private Node root;
	private int size;

	public BinaryTree() {
		this.root = this.takeInput(null, false);
	}

	public Node takeInput(Node parent, boolean ilc) {

		int cdata = scn.nextInt();
		Node child = new Node();
		child.data = cdata;
		this.size++;

		// left
		boolean hlc = scn.nextBoolean();

		if (hlc) {
			child.left = this.takeInput(child, true);
		}

		// right
		boolean hrc = scn.nextBoolean();

		if (hrc) {
			child.right = this.takeInput(child, false);
		}

		// return
		return child;
	}

	public boolean structurallyIdentical(BinaryTree other) {
		return this.structurallyIdentical(this.root, other.root);
	}

	private boolean structurallyIdentical(Node tnode, Node onode) {
		int hls_t = this.height(tnode.left);
        int hrs_t = this.height(tnode.right);

        int heightDifference_t = Math.abs(hls_t - hrs_t);

        int hls_o = this.height(onode.left);
        int hrs_o = this.height(onode.right);

        int heightDifference_o = Math.abs(hls_o - hrs_o);

        if(Math.abs(heightDifference_o - heightDifference_t) == 0) {
            return true;
        }
        else {
            return false;
        }
	}

    private int height(Node node) {

        if(node == null) {
            return -1;
        }
        int lheight = this.height(node.left);
        int rheight = this.height(node.right);

        int height = Math.max(lheight, rheight);

        return height + 1;
    }

}

}

structurally identical means that the structure of the tree should be same…consider root node of both the trees if first roots left child is null then second roots left child will also be null(if trees are structurally identical)…same goes for right…you have to check this for every node… try to do this recursively…

HINT:traverse both the trees along the same path and check whether node exists or not