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Infosys DSE Interview Experience 2021

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  • Difficulty Level : Basic
  • Last Updated : 29 Jul, 2021
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I got a PPI interview opportunity for the role of Digital Specialist Engineer after clearing the first round of HackWithInfy 2021. The first round consisted of 3 questions- 1 Easy, 1 Medium, and 1 Hard. I was able to solve one question completely and passed 60% of the test cases of another question in this round. My interview was scheduled for 26th July 2021 on Webex online platform. I was informed 6 days before, about the 40-minute interview.

My interview was quite different from other candidate’s interviews. For example, Though it was a technical interview, I was not asked any questions from Projects (no technology-related questions), DBMS, OOP. Also, he has not started my interview with “introduce yourself”! The interviewer looks aged and has 10 years of experience in Infosys.  He asked me the following questions:

  1. Where are you from, college and stream?

    Me: Answered

  2. Is 87 a prime number?

    Me: No, it is divisible by 3.

  3. Is 187 a prime number?

    Me: FIrst I answered yes in hurry, then he asked me to recheck, then I told him that number is divisible by 11.

  4. Is 437 a prime number? 

    Me: After doing calculations, I answered it is divisible by 19.

  5. Tell me a square of 28 without using pen-paper.

    Me: I answered numbers from right to left, I am not sure it was correct or not.

  6. Tell me the square root of 187 without using pen paper.

    Me: I told him it is between 13 & 14, I can not calculate exactly.

    He: Yes, that is fine.

  7. Find the last two numbers of the series: 1, 2, 2, 4, 4, 6, 8, 8, 16, ?, ?

    Me: I took 2-3 minutes and I told him 16.

    He: it is wrong, recheck.

    Me: Then I told him my approach that I can see that powers of 2 are repeating.

    He: Yes you are close, try to find an answer.

    Meanwhile, he wanted to take another interview with another candidate (strange…right?) so he gave me the below question and told me to solve the 7th & 8th both.

  8. Write a program of Longest Common Subsequence (LCS) on paper in any language. wait in the lobby, I can monitor (as the camera is on ) you, so don’t try to move away. 

    Me: I took 5 minutes to code (on paper) LCS using DP and wrote 2 examples in tabular form.   Then I cam to series (7th Q), I observed carefully and found an answer. (10 & 32, check here: Then I wait for 8-10 minutes and then he again switched me into the meeting.

    He: Send a photo of the LCS code to me in Whtsapp (He gave number) and tell me the answer of the series.

    Me: I send a photo and gave an answer to the series.

    He was satisfied with my answer. You can refer python implementation of LCS here.

  9. Difference between Authentication and Authorization?

    Me: I told him about authentication, but I was not sure about authorization so I said I don’t know.

    You can check the difference here(

  10. What is HTTP? what are the methods?

    Me: I told about HTTP. I told him two methods: Get and Post.

  11. What is idempotent?

    Me: I don’t know the exact meaning, but I heard “idempotent matrix” in linear algebra, By squaring any matric if we get the same matric then that is an idempotent matrix.

    He: partially correct.

    I think he expected the meaning of idempotent from me.

  12. Any questions from me?

    Me: I asked him 2 questions.

That’s the end of the short interview, Aged and Experienced people have their own methodologies to take an interview. Half of the questions were checking my numerical ability. So this is how my interview is slightly different from others. Good luck for your interviews!

My Personal Notes arrow_drop_up
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