Paytm Interview Experience | Set 25

I was interviewed by Paytm  for a Software Engineer profile.

Round 1: “Coding Round” 

The coding test was taken on Mettl. Two questions, 1 Hr time.

1. An adhoc problem. Given an array of marks for ‘n’ questions. Find the minimum total marks.                       Constraint: two questions cannot have same mark.
2. A DP problem. The question was put into a story. It was on Longest Palindromic Substring. https://www.geeksforgeeks.org/longest-palindrome-substring-set-1/

Each question had around 10-12 test cases to be passed. A list of candidates was announced for F2F interview.

It was going to be a long day! Phew!

Round 2: F2F (1 Hr)

Basic Introduction. The interviewer went through the Resume, asking question on it.

• https://www.geeksforgeeks.org/add-two-numbers-represented-by-linked-lists/ 
• https://www.geeksforgeeks.org/reverse-a-linked-list/
• https://www.geeksforgeeks.org/level-order-traversal-in-spiral-form/

Was asked to implement Immutable class. A detailed discussion on Immutable classes.
Was Asked to implement and explain inner working of Thread Pool and Semaphores.

• https://www.geeksforgeeks.org/create-immutable-class-java/
• https://www.javacodegeeks.com/2016/12/implement-thread-pool-java.html

Round 3: F2F (1 Hr)

Basic Introduction. The interviewer went through the Resume, asking question on it.

A detailed discussion on HashMap and inner working of it. Discussion on how/when to increase size of it. Discussion on threshold value and load Factor.

http://javaconceptoftheday.com/initial-capacity-and-load-factor-of-hashmap-in-java/

Was asked to write production code for implementing a LinkedHashMap where items when retrieved comes out in the same order as inserted.  An update on already present element makes it as a new element.

Production level code for three functions were asked to implement with every case covered:

• add()
• delete()
• printAll()

Asked me about its Time/Space Complexity.

Round 4: F2F (~35 Mins)

Basic Introduction. The interviewer went through the Resume, asking question on projects I’d on it in detail.

Was asked to explain working of a Trie, as I had used it in one of my projects. Also few Question related to OS (I don’t really remember them now!)

Round 5: F2F (HR Round)

Basic HR questions. It went on a fun track asking about travel and places to visit around:p

All Practice Problems for Paytm !