Interview Questions for experienced professionals: Part 1

This article is for those who are prepaing for any technical job interview. Different organisation have different interview process and here I am sharing the interview of one of the consulting firms.

Interview was categorised into multiple sections to understand T shaped skills. T shaped skills accesses a candidate on core expertise(depth of understanding) and other technical skills(breadth of concepts). I have catagorised the interview into sections which includes, Algorithms, SQL Server, Innovative Ideas, Technical Knowledge and so on.

You may check your knowledge as well. Try it once.

Algorithms

Q: How to swap the values of two integers with using additional memory?

Ans:

public static void SwapInt()
        {
            int a = 25;
            int b = 35;
            
            a = a + b;
            b = a - b; 
            a = a - b;
            Console.WriteLine("a=> " + a + " b=> " + b);
        }

Q: How to find duplicate in an array? Please not there is only one duplicate value.

Ans:

Alternative 1

public static void DuplicateInt()
        {
            int[] intarr = {1, 2, 3, 4, 2, 5, 6};
            for(int i=0 ;i<intarr.Length-1;i++)
            {
                for(int j=intarr.Length-1;j>i;j--)
                {
                    if(intarr[i]==intarr[j])
                    {
                        Console.WriteLine("Duplicate is " + intarr[i]);
                        break;
                    }
                }
            }
        }

Alternative 2

public static void DuplicateInt()
        {
            int[] intarr = {1, 2, 3, 4, 2, 5, 5};
            Array.Sort(intarr);

            for(int i=0 ;i<intarr.Length-1;i++)
            {
                    if(intarr[i]==intarr[i+1])
                    {
                        Console.WriteLine("Duplicate is " + intarr[i]);
                        break;
                    }
                }
            }
        }

Q: How to reverse the string without using additional memory?

Ans: I could think of this way which is using additional memory. Please share if you have logic which would do the reversal of string without using additional memory.

 public static string StringReverse(string str)
 {
     char[] ca = str.ToCharArray(0,str.Length);
     Array.Reverse(ca);
     return new string(ca);
 }

Q: Push all zero elements in the last of the array.

Ans:

public static void ZeroBack()
        {
            int[] intarr = {1, 2, 0, 3, 4, 0, 2, 5, 0, 6};
            Array.Sort(intarr);
            Array.Reverse(intarr);     
        }

SQL Server

Problem Statement: There are two tables 1. Bank_Account_Customer 2. Customer

Bank_Account_Customer

bank_account_id

account_name

balance_amount

Customer

customer_id

customer_name

bank_account_id

Find all customers who have balance_amount>5000.

Solution:

Select c.customer_name, c.customer_id from Bank_Account_Customer b, Customer c where b.bank_account_id = c.bank_account_id && b.balance_amount > 5000;

The above can be done using Joins as well.

Innovative Ideas

Problem Statement: Design a vending machine with new approach, keeping Covid in mind.

Solution: We may use Scan code where an user can scan the code of vending machine and make the payment online there itself. As payment will be done, instruction will be sent to vending machine to dispense the item.

Problem Statement: Design elevator solution with new approach, keeping Covid in mind.

Solution: We may use voice recognition feature, one can speak on which floor he/she would like to go and that floor number will be highlighted.

There can be N different ways to solve above problems. I have shared what came to my mind that moment of time.

Technical Knowledge

Question: What is difference between Abstract class and Interface and share the scenerios when should we use what?

Answer:

Abstract class can have implementation as well, however Interfaces only have signatures.
Multiple inhertance can't be achieved using Abstract class, however we can inherit multiple interfaces.
We can use any access modifier in Abstract class but in interfaces everything is public.

When we have the requirement of a class which contains some common methods and properties whose implementation is different for different classes, we should use abstract class.

Question: What happens when we concatenate string using + sign? What is efficient way to do it?

Answer: String is immutable in .Net which means everytime you use string class method, no matter name is same or different, a new string object is created in memory. More string operations means more memory consumption.

StringBuilder class provides the way to deal with memory efficiently. If string operations are common in your code, use it. It is not recommended to use when string operations are few.

Next round was on Agile methodology, NFRs(Non functional requirements), DevOps, Root cause analysis approach. Interesting question were asked and discussion was quite impactful.

The noblest pleasure is the joy of understanding