Sirion Labs
Interview:
Venue:
Palm something, Gurgaon. Within 15 minutes ride from Sikandarpur
metro station. Auto wala will charge around 50 bucks to land you straight up
there.
Date
: 3 August 2013
Round I:
First round is Java basics. Well, not that basic. The questions
keep getting twisty as you move through the paper. Some of them are plain
silly. And yes, there are a couple of questions relating to data structures as
well.
In total there are 16 questions.
No marking at all. They will simply discuss the solution to the
answers. So be cautious about any guess that you make. In the interview they
will discuss any question that you marked as wrong or any such question that
turned out to be right in your case, but the majority got it wrong.
Questions of first round (in no particular order):
1. class A
{
public static void X()
{
Y();
}
public static void Y()
{
System.out.println("parent");
}
}
public class B extends A
{
public void Y()
{
System.out.println("Child");
}
}
What
will the following code snippet print?
B.X()
?
Ans.
Explanation:
From the first look it appears that either Parent or Child will
be printed. But, there’s a catch. All the methods are static and static methods
cannot be overridden as they are properties of class.
2. try
{
int a = 5;
System.out.println("Try");
}
catch(Exception e)
{
System.out.println("Exception is ="+a);
}
What
will be printed on running the above code snippet?
Options:
A) Try
B) Exception
C) Run
time error
D)
Compile time error
Ans.
D) Compile time error
Explanation:
You may spend a lifetime trying to figure out what’s wrong with the above code
and still write A with an uneasy feeling that something is definitely amiss,
maybe I am just overlooking it. Your gut feeling is correct. Something is
amiss. But it’s just silly. Did you notice that the variable ‘a’ is being
called in exception block while its scope ends in ‘try’? See, it’s silly. The
code will simply give a compile time error.
3. A
very long question. First it lists the definition of in order, pre order and
post order traversal. It refers to post order as reverse order. Whoever
came up with that? Then it innocently gives the pre order traversal of
a tree. ABCDE. As expected, the question asks to come up with
the corresponding in order and post order traversal.
Options:
A) CBDAE,
CDBAE
B) Insufficient
data, CDBAE
C) Insufficient
data, CABDE
D) Insufficient
data, insufficient data
Ans.
Explanation:
This question can have two possible answers.
In option A if we consider the in order traversal ‘CBDAE’ as part
of the question then CDBAE is indeed the correct post order traversal. Hence, A
is correct.
Both, B and C are incorrect because we cannot find the post order
traversal without knowing both the in order and pre order traversal.
D can also be correct as only pre order traversal cannot give us
both the post order and in order traversal.
4. String a = null;
String b = "xyz";
String c = a+b;
System.out.println("c");
What
will be the output on running the above code snippet?
Options:
A) xyz
B) nullxyz
C) Complie
time error
D) Run
time error
5. public int method(int n)
{
int result = 0;
n <<= 1;
while (n > 0) {
result += (n / 2) % 2;
}
return result;
}
The
method is called as method(13977) or some very large odd number. What will the
method return in the variable result?
Ans.
Explanation:
N<<=1 simply multiplies N with 2. It is equivalent of n*=2.
6. The
entire code for reversing a link list. They just removed the initialization
part and the part inside the loop. You have to write that part.
7. int result =0;
for (int i =0; i< 10; i++)
{
for (int j=0; j<10; j++)
{
result+=i+j;
}
}
What will be the value
of result?
Ans.
Explanation:
The catch in this question is that i+j will be calculated after result+=i is
calculated so result will eventually be ∑(10*i) i.e. (10*0+10*1+10*2…….+10*9).
There were 9 other questions. Most of
them, related to inheritance.
Round II
All the questions were related to algorithms. You can choose any
language you wish.
1. There
is a 2-D matrix of 0’s and 1’s. Given a 2D array of
1's and 0's, find the size of the largest block of 0's. For example the
following 2D array:
int[][] array = {
{1, 0, 1, 0, 0, 0, 1,
0 },
{1, 0, 0, 0, 0, 0, 1,
1 },
{1, 1, 1, 0, 0, 0, 1,
1 }
};
Will return
"9", because there is a 3x3 square of 0's, and that is the biggest
block of 0's in the 2D space.
2. Find
the largest distance between two nodes in a binary tree.
The
diameter of a tree (sometimes called the width) is the number of nodes on the
longest path between two leaves in the tree. The diagram below shows two
trees each with diameter nine, the leaves that form the ends of a longest path
are shaded (note that there is more than one path in each tree of length nine,
but no path longer than nine nodes).
The
diameter of a tree T is the largest of the following quantities:
*
the diameter of T’s left sub tree
* the diameter of T’s right sub tree
* the longest path between leaves that goes through the root of T (this can be
computed from the heights of the sub trees of T)
Interview:
1. Implicit
objects in JSP?
2. What
happens if destroy() is called on a servlet object?
