# Payu Interview Experience | Set 3 (On-Campus)

• Last Updated : 15 Sep, 2014

Recently Payu visited our campus and its process of selection was as follows:-

Online Test :
15 technical questions + 5 Coding Questions(I solved all the coding and about 10 technical Questions). Luckily i got shortlisted for the personal interviews. There were 4 technical rounds and 1 HR round.

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Technical Interview 1 (30 mins):
1. Introduce yourself.
3. Code for a modified least common ancestor of two nodes in BST (complete working code with boundary conditions needed).
4. given two strings, remove the characters from string1 that appear in string2 in O(N) and constant space.(code was needed).
5. modified DP problem of Rod Cutting.(No code needed, we wanted the mathematical equations and how to solve by DP approach).

Technical Interview 2(45 mins):
1. Introduce Yourself.
2. Asked me to write the complete code for insertion and deletion in AVL Trees implemented using maps.(I mentioned it as one of my projects).
I was not able to write complete code and then asked me if can only explain it(He was OK with that).
3. Discussion about how to maintain session of users on web.
5. Given an array of integers, find all pairs with a given sum K.
6. Given an array of integers, find all pairs (a, b) such that (a % b )= k. (k was given as input). O(N) solution was expected.
7. Given an array of integers, find all subsets of size 2 and size 3 such that in subset of size 2 , a+b = K and in subset of size 3 , a+b+c = K.
(K given as input). needed O(N) solution.
8. Few questions on resume and achievements.
9. Puzzle: Given 16 horses find the top 5 horses in least number of races. Only 4 horses can take part in a single race.
(my starting approach was correct, but later on asked for hint), finally solved.

Technical Interview 3(30 mins) :
1. Introduce Yourself.
2. Why not higher studies.
3. Why Computer Science.
4. Gave me a paper with a single problem on it :- Given an English Dictionary that contains only valid English letters. We need no to worry
about the way English Dictionary was implemented. Given some input and the corresponding output , I was asked to write the code for
getting the required outputs. Once you are done with small cases he kept on giving more complex inputs.
He was actually checking by understanding of the Recursion, base cases and Problem Solving Approach. Code was needed for every case.

Technical Interview 4(40 mins) :
1. Introduce yourself
2. What is KMP Algorithm. Write code for preprocessing function.
3. Difference with Http ans Https.
4. How Security is provided on network.
5. DBMS : Discussion on Normalization and its significance and various Normal forms(1st NF, 2nd NF, 3rd NF, BCNF).
6. OS : Explain Paging with Example.
7. Design Patterns: Asked me to implement Singleton Design Pattern.(Asked for hint and then implemented it).
8. Some easy questions on Arrays again.
9. Asked to write code for Vertical Tree Traversal by considering all boundary cases and all test cases. (I took some time then coded using
map > ). He was okk with my code.
10. Asked me the same English Dictionary question, I told him that I have already solved it.
11. How to implement Mutual Friend Feature of FaceBook.
12. How to implement top 5 friends feature.