PayU Interview Experience – Senior Software Engineer

Round 1:

  1. How will you handle DDoS attack?
  2. Design a login API which is secure even if SSL certificate is compromised.
  3. How will you design an API whose response will have the response from 3 other different microservices?

Round 2:

  1. Detect a loop in a singly linked list.
  2. Find the Missing Number.
  3. You are given 8 identical looking balls. One of them is heavier than the rest of the 7 (all the others weigh exactly the same). You a provided with a simple mechanical balance and you are restricted to only 2 uses. Find the heavier ball.
  4. Project discussion.

Round 3:

  1. Maximum Path Sum in a Binary Tree.
  2. For what value of n following code does: (n & (n-1) == 0)
  3. What is the Python decorator? Give an example.
  4. Difference between Python 2 and 3.
  5. How does OAuth 2 work? What kind of problem it’s solving?
  6. OAuth 2 grant types?
  7. What is the meaning of OAuth 2 token bearer?

Round 4:

  1. Design a notification system for following types of notifications.
  2. Low priority notification – Should be delivered within an hour.
  3. Regular priority notification – Should be delivered within 30 minutes .
  4. High priority notification – Should be delivered within 30 seconds .

       Note: Notification should not be delivered more than once.

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