Please explain already answered Question

Question

Link to the question - https://gateoverflow.in/20611/tifr2011-b-30

Someone please simplify that question and explain.

Answer 1

Ok so we start with small array of size n = 3

Let the array A looks like:-

3

1

2

and Let array B is empty:-

Now in the question, it is given that we will be going to fill the array B with the following equation i.e.

B[A[i]] = i / for all i and i = 1,2,3

Now consider the following table to fill the array B

i	A[i]	B[A[i] = i	View of Array B
1	3	B[3] = 1	{_ , _ , 1}
2	1	B[1] = 2	{2 , _ , 1}
3	2	B[2] = 3	{2 , 3 , 1}

now after that array B will look like this-

2

3

1

you can see that this is also an permutation ( or another way of arranging the elements) of the elements 1,2,3.

Or in other words, you can say that it is a permutation of array A.

Hence answer is Option B)

Hope this helps ...