Structurally Identical

can anyone tell me why using build function gives wrong answer and using buildtree gives right what is wrong in build function plz elaborate
also my two testcase are failing plz tel what is wrong in my code

Here as well, goes the same logic.

I hope I’ve cleared your doubt. I ask you to please rate your experience here
Your feedback is very important. It helps us improve our platform and hence provide you
the learning experience you deserve.

On the off chance, you still have some questions or not find the answers satisfactory, you may reopen
the doubt.