Paytm interview experience Python developer | (2.5 years)

For Paytm Bangalore location Round 1: Pen paper round consists of 22-25 questions(1.5HR)

• 6 questions from SQL based on SQL joins and basic aggregate functions. Given 2 table employees table and employee's manager table. 3 out of 6 are from self join.
• 1 Question from a data structure - Design a data structure support the specific type of searching from given large dataset if the dataset is ["bear", "bell", "buy", ......] and input is "be" then the function should return all possible values.  output - "bear", bell. Answer - Modified Trie data structure.
• 12-15 Questions from python easy to hard level some basics of  Python list comprehension, decorator, generator, iterator, etc.

Round 2: Face to face(1.2HR) This was 1st face to face round the interviewer was very humble.

• He started with my project discussions, asked me to explain any project, and deep discussion on that project.
• Hospital database design fully normalized, some easy and complex queries to get data from the database, don't forgot mention keys like primary key, foreign keys.
• Identify two people are friends on Facebook, design efficient data structure and write production level code for searching.

Round 3: Design round machine+F2F(2.5HR) This was a API design round on machine, no language restriction.

• A problem statement was given, design an API to get user activity logs. Design API and data base schema. Major focus on data base design don't forget to mention keys constraint. After 2.5 Hr deep discussion on database design.

Round 4: Face to face(1HR) This round was mix of data structure and algorithm, database, and my projects. Interviewer asked me question on my recent project, extend the current database design to add some functionality. He asked me total 5-6 question including algorithm question.