1) Can a class with a private destructor be instantiated?

That is a tricky question because the answer is both yes and no.
Yes, it can be instantiated on a heap.
No, it cannot be instantiated on a stack.

A class with a private destructor cannot be instantiated on a stack (Object obj) because the compiler cannot call a destructor.
It is okay to instantiate it on a heap because we control when the destructor is called.
A class with a private destructor can destroy itself (delete this).

So when do we need a class that has no accessible destructor?
A class that counts references should not be deleted by a user because the user does not know if all references have been released.

2) What is a function object (FUNCTOR)?

An object that overloads the function call operator ()

class compare
{
public:
    bool operator()(int A, int B) const
    {
        return A < B;
    }
};


And here is a usage pattern:


template <class Functor>
void sorta(int* items, int count, Functor pred);


3) Find n-th, from the tail, object in a linked list.

The question can be easily solved in O(n) time with two pointers.
Start the second pointer n iterations after the first pointer.
Once the first pointer has reached the end of the linked list, the first pointer is at n-th element from the end.

4) Implement a URL caching mechanism

Cache speeds up fetch requests by storing results in fast memory.
All practical cache algorithms, sooner or later, must expel items from cache.
Least recently used (LRU) algorithm simply evicts items that are least used. LRU is frequently implemented using a priority queue.
CLOCK algorithm is implemented using an array and it evicts the first unused item that it finds.

5) How do virtual functions work?

A v-table is constructed for each class that has virtual members.
V-table contains addresses of all virtual functions, and is created when a class is instantiated.

6) Is it possible to have a virtual constructor?

No, because the v-table is not yet available when the constructor is executed.

7) What data structures would you use to store a dictionary of names?
8) What is template metaprogramming?

Metaprogramming is the ability of a program to manipulate other programs as data.
Metaprogramming is frequently achieved via reflection or templates.

Here is an example of metaprogramming in C++:


template <int N>
struct Factorial
{
    enum { value = N * Factorial<N - 1>::value };
};

void fact()
{
    int x = Factorial<4>::value; // == 24
    int y = Factorial<0>::value; // == 1
}


9) Is there a performance difference between a) and b) loops?

a. for (unsigned int i=0; i<10; i++)
b. for (unsigned int i=0; i<10; ++i)

10) Define a Singleton


class Singleton
{
public:
    static Singleton *instance (void)
    {
        if (instance_ == 0)
            // Critical section.
            instance_ = new Singleton;
        return instance_;
    }
private:
    static Singleton *instance_;
};


1. What is a standard Microsoft technology stack for a database driven web application with reporting?
2. What are C# generics and why they are useful?
3. What are Lambda expressions and what have they replaced?
4. What is LINQ used for and how does this benefit the programmer?
5. What are CURSOR in T-SQL and how can they be helpful?

1. ADO and also Microsoft Reporting Services are used for DB driven web applications with reporting.
2. Generics are similar to templates in C++. Generics allow to defer specifications of types until class/method is declared/instantiated.
3. Lambda expressions replaced anonymous methods syntax that allow to declare code inline
4. LINQ is Language Integrated Query – it transforms database development model into an object oriented one so the developer who know OOP does not have to go deep into SQL.
5. CURSOR allows to loop through data – row by row.

2) 4 people must cross a bridge.
a.    Only 2 people can walk a bridge at the same time because it is dark and they have to carry a flashlight with them.
b.    Once 2 people cross the bridge one of them must return the flashlight so that the rest can cross it
i.    First person can cross the bridge in 10 minutes
ii.    Second in  5 minutes
iii.    Third in 2 minutes
iv.    Fourth in 1 minutes
How long will it take them all to cross the bridge?
They are in hurry and must do it as fast as possible

3) Write an algorithm to convert integers to words.
a.    i.e. 1234 must be spelled as one thousand thirty four

4) Write an algorithm to reverse a single-linked list

5) Write an algorithm to draw a star with n corners
a.    You have 2 functions to use: moveto(x,y) lineto(x,y)

6) Write an algorithm to add a node to a singly-linked list
   
7) You have a table A that contains managers with their ManagerID and Name and table B that contains employees with their EmployeeID, Name, and reference to their manager (ManagerID).
a.    Write a SQL statement to display all Employee names with their manager names.
b.    Modify the statement to display employees that do not have a matching manager

8) You have a b-tree How would you store it in a relational database? (Design the schema)

A recruiter from Google contacted and asked if I want to have an interview with a Google engineer,
It is hard to say no to Google; after all, in terms of benefits, working for Google is the second best thing after having your own business.

Two weeks have passed and no word from Goggle.
Well, I thought, they have so many candidates that have probably forgotten about me.
But in another week, I received an e-mail from the same recruiter asking to select your top three areas of my developmental expertise.
1) Web applications and multi-tiered systems
2) Database internals
3) Windows development
And she also asked me if I know someone who already works for Google. I found two references (in retrospective should have said no).
In a week another recruiter contacted me and asked to rate myself:
   0 – Indicates you have NO EXPERIENCE – that is fine but please indicate
1-3 – Indicates you can read / understand the subject area, but would not be comfortable implementing anything in it.
4-6 – Indicates you are comfortable with the subject area and all normal / routine work in it.
   7 – Indicates that you are extremely proficient and have deep technical expertise in the subject.  You would be comfortable with personally designing and implementing any project in that area.
   8 – Indicates that you are almost an expert from fundamentals to advanced concepts.
   9 – Indicates you are an expert and could have written a book on the subject, but didn’t.
 10 – Reserved for those who are recognized industry experts in a field (i.e. wrote a book on the subject).

3 TCP/IP Networking (OSI stack, DNS etc)
3 Unix/Linux internals
6 Unix/Linux Systems administration
6 Algorithms & Data Structures
5 C
8 C++
0 Python
4 Java
4 Perl
6 Shell Scripting (sh, Bash, ksh, csh)
8 SQL and/or Database Admin
4 Management

In a couple of days the second recruiter scheduled a phone interview with him for the following week.
Five minutes before the scheduled interview I received and e-mail from the recruiter saying that he has an emergency meeting and would like to reschedule the interview for the next week.
Next week he called and asked some questions:

1. Convert a number from decimal to binary.
2. Describe some basic data structures.
3. Describe some basic search algorithms.

1. How many bits needed to represent 1000000?
2. What is the complexity of searching in a balanced binary search tree?
3. What is the complexity of insertion in a hash table?
4. Find two numbers in an array whose sum = X.