I have implemented the code for TREDIFF as explained in the POST CODECHEF DISCUSSION by @rajarshi_basu
Link to the code : Tree Difference - May Lunchtime codechef - Pastebin.com
I am getting TLE for the second task.
What is wrong in my code? Please tell me ? I was unable to figure out.
I can’t see anything that would make it O(N \times Q) or anything like that, so I suspect it’s only just timing out by a small amount, most likely due to your unnecessary use of a std::set.
(I have a testcase here that takes your solution 3.83 seconds on my laptop, but my laptop is slower than Codechef’s servers, so I’m not sure if that counts … )
Without using sets there may be a chance of putting duplicate values which eventually gives 0 everytime. Therefore to avoid that i am using set. set operations usually takes O(1) right?
No, set::find and set::insert take O(\text{size of set}). They also have a fairly high constant factor.
Granted, my_set in this case won’t contain more than 100 (a constant) elements, but it’s still slowing things down.
How can i optimize this code to make it work. I tried to implement optimal one, but i failed 
Think it through - I’ve already suggested one think that is probably causing it to TLE! 
A hint, to get you on the right track - what is my_set doing? Is there a way of doing it without using something as slow and expensive as a std::set? The Editorial solution doesn’t use one!
I will try to use a bool array
Here’s a testcase to practice on 
Do you write a program to generate these kind of test cases?
Yes
Does any ide accepts this large test case?
I don’t know, sorry - I don’t use an IDE for CP.
How can i do then? Codechef is not accepting this one
Compile and run it locally.