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I want to know that in ISRO 2017 there were 2 questions in that answers of questions in ISRO Official key and GO key mismatches,

for question 1) http://gateoverflow.in/128485/isro2017-53

GO has given no answer and ISRO Official key has given A as ans ,

for question 2) http://gateoverflow.in/128489/isro2017-16

GO has given B as answer and ISRO Official key has given D ans ,

Does any one can give some suggestion about these questions??

any suggestions would be appreciated..

posted May 25, 2017 in Others by (439 points) | 618 views

8 Comments

http://gateoverflow.in/128485/isro2017-53

option D is more appropriate . Option A is one of the correct answer , if you see the answers provided in GO , you will get to know it.

http://gateoverflow.in/128489/isro2017-16

option B is more appropriate . The options in question is actually wrongly represented which makes no sense .

So both can be challenged .

So in case of wrong answers

Will isro team give marks to all or they will revise the answer keys and then evaluate the final score?

My two cents:


In question 1, they have assumed the structure to be something like this:

Implementing Doubly-Linked Lists

Option D is "Depends upon the nodes of the dll."

If option D were to be: "Depends upon the structure of the dll." Then it would have been correct.

Options B and C are ruled out because irrespective of the structure of the dll, atleast 2 pointers will be updated.

(Option D is too vague. But you wanted justification so you got one!)


 

In question 2, we can't claim the given statements to be either true or  false.

Our implementation  may or may not require that:

                  "Insertion of an element be done at the last node of the circular list"

Similarly,

Our implementation  may or may not require that:

                  Deletion of an element be done at the last node of the circular list"

(Think about the implementation of stack and queue using circular list.)

(Think about maintaining a sorted circular list.)

Hence, it boils down to our requirement.

Therefore, option D makes sense here.


 

@Higgs

In your Question 2 , isro paper setters use the word " should be " that means " Insertion of an element should be done at the last node of the circular list " that should word makes it false statement , hence option B is more appropriate.
I thought there were 4 mismatches in all. Last time they had plenty and after debate, they corrected more than half of them.

@Bikram Sir 

http://gateoverflow.in/128485/isro2017-53

I don,t think D is correct here.

What do you understanding by Depends on the nodes of doubly linked list.?

According to me, questions makes no sense here.

Unless it is explicitly mentioned  "where to insert a node" in question we can,t say anything here.

However one of the possible answer is A.But question is not framed properly so here also No option is correct.

Yes @Manoj

You are correct ,

" Depends on the nodes of doubly linked list" really makes no sense though  option A means 4 is also not complete answer .

Options are  wrongly  framed  but having one close to correct answer is better than no answer , right ?

Note: In no way, I am trying to pitch the idea that ISRO's ans. key is correct.

I am just trying to come up with the thought process that might have lead to the disputed answers.

I too think that these answers should be challenged (of course if allowed).


Let me elaborate on what I meant:

 

Application A Insertion of an element should be done at the last node of the circular list Deletion of an element should be done at the last node of the circular list
Application B Insertion of an element should be done at the front of the circular list Deletion of an element should be done at the last node of the circular list
Application C Insertion of an element should be done at the last node of the circular list Deletion of an element should be done at the front of the circular list
Application D Insertion of an element should be done at the front of the circular list Deletion of an element should be done at the front of the circular list

So it depends upon our application.

 

We can't claim that these statements:

  1. Insertion of an element should be done at the last node of the circular list.
  2. Deletion of an element should be done at the last node of the circular list.

or these statements

  1. Insertion of an element should be done at the first node of the circular list.
  2. Deletion of an element should be done at the first node of the circular list.

(and similarly other possibilities for insertion and deletion...)

are true.

 

But can we claim that these are false??

What if our applications requirement is such that insertion and deletion must be done in this manner??

 

That's why I think better ans is:

"Depends upon our requirement"

 

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