Lenskart Backend Developer Interview Experience

How I have applied?

Hello, I connected with the people of Lenskart by sending connection requests with an invite. I sent requests to around 30-40 people out of which 5-6 people connected and 2-3 agreed for providing referrals. They asked for my resume and Job Id. 

Invite message 

Hello ABC, 

I am Harshit working as a software engineer with 1.5 experience. I would like to connect with your network and explore opportunities for SE/SDE/Backend engineer position at Lenksart.
Thanks & regards

After a few days, received a call from HR. They asked about my skills and background. And why I want to switch. After that, schedule an interview with one of the experienced SE. And this is how communication was established.

Tech Interview 1 

Duration - 45mins

Both joined at the time. Started with a brief introduction of both. Then asked about the technologies worked on, my current company's work, and my role. Then, switched to DSA questions

Q1.  Given two arrays A and B. A sorted in non-decreasing order and B sorted in non-increasing order. Merge both arrays such that the resulting array is in descending order (no duplicates)

Testcase

I/p A[] = [ 2 5 7 8 9 ]
I/p B[] =  [ 8 6 4 3 1 0  ]
O/p C[] = [9 8 7 6 5 4 3 2 1 0]

I started telling them about possible approaches. But the interviewer himself didn't know the solution so, he just agreed with what I said. It seemed that the question was picked at the point of the interview only. 

Anyway, I explained the solution and started to pseudo-code the solution. The interviewer doesn't seem to be satisfied, anyway, he asked a few questions and boundary conditions about the solution. The problem was solved.

Pseudo-code

i = a.length - 1; 
j = 0;
k = 0;
while(i >= 0 && j < b.length){
    if(a[i] > b[j])
         c[k] = a[i];
         i--;
     else if (a[i] == b[j])
         c[k]  = a[i];
         i--;
         j++;
     else
         c[k] = b[j];
         j++;
     k++;
}
while(i < a.length){
     c[k++] = a[i];
}
while(j >= 0){
     c[k++] = b[j];
}

Q2. Given an array of strings, return the first anagram from  array 

(somewhat like this)

Testcase:

I/p S[] = [ bad , abd , bat , tab ] 

O/p Res[] = [ [ bad  , abd ], [ bat , tab ] ]

Asked some questions about problem and started thinking and telling my approach. Was able to pseudo-code it, 

int count[26];

for(String s : str){

    for(int i =0;i<s.length;i++)

        count[s[i] -'a']++;

     String temp = count.toString()

     if(hashset.contains(temp)) 

         return s;

     hashSet.add(temp);

}

then asked questions about its time and space complexity. Interview done.

Technical Interview 2

Duration - 60mins

Next day. Started with a brief introduction of both. Focussed more on programming. Asked fundamental questions from OOPs. Asked to present screen, gave me an input/ output question

public class Test {

    public static void main(String[] args) {

       Parent p=new Child();

       p.myMethod();

       p.myMethod2();

    }

}

class Parent {

    private String name;

    public void myMethod(){

        System.out.println("i am in parent");

    }

}

class Child extends Parent{

  @Overriding

    public void myMethod(){

        System.out.println("i am in child");

    }   

 public void myMethod2(){

        System.out.println("i am in parent 2");

    }

}

Asked about the outputs. And some variations of it, concepts behind this code (Polymorphism). The interviewer this time, was active and interested in listening.

Then asked me about my favorite data structure. So, I told stack, therefore he asked me about a linked list problem. 

Delete the Kth node from the end of the linked list. here

I/p

1 -> 2 -> 3 -> 4 -> 5 -> null 

n = 2 

O/p

1 -> 2 -> 3 -> 5 -> null 

The first approach I tell was to iterate to calculate the length of LL. Then again traverse and delete (length - k)th node. They found that trivial and asked for a better approach. 

Therefore, I told the other approach. Using two pointers start and shifted. Same as GFG.

They asked me to code it and ran it locally. So wrote compilable java code. But I was missing boundary conditions and the code was not working properly. It took some time and help to resolve that. In the end, time was over however the solution worked at the end. Looked convinced

class Test{

     static class Node{

         Node next;

         int key;

         Node(int k){

             key = k;

             next = null;

         }

     }

     public static void main(String args[]){

         Node n1 = new Node(1);

         Node n2 = new Node(2);

         Node n3 = new Node(3);

         n1.next = n2;

         n2.next = n3;

         System.out.println(deleteFromEnd(n1,3).key+" "+n1.next.key);

     }

     static Node deleteFromEnd(Node head , int n){

         Node start = head;

         Node shifted = start;

         int i = 0;

         if(head == null )

             return head;

         while(i < n && shifted != null){

             System.out.println(shifted.key);

             shifted = shifted.next;

             i++;

         }

         Node prev = null;

         while(shifted != null ){

             start = start.next;

             prev = start;

             shifted = shifted.next ;

         }

         if(prev != null)

             prev.next = start.next;

         else

             head = head.next;

         return head;

     }

}

Now after that interview, they took 15 days to get back. I thought the process was over and I was rejected. But after 15 days received a call from HR for the final round. Surprised, why so late. The final round was Techno-HR.

Techno-HR round

Duration - 40mins

Again same brief intro, and programming question. 

Remove duplicate words from a string. 

And SQL inner join query to count employees with given department name.

Then asked about my current CTC and experience, and I told them my current CTC and I have  1.5 years of experience. Then, asked about my expectation. So I told about what work I would like to do and expected CTC. Everything went right. I also asked questions about the team they are working with, the work culture, and the location. And they gave an insightful answer on that. 

I was then offered the role.

Thanks for reading. Hope that helped. 

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