PayPal Interview Experience for SDE-1 (On-Campus)

Eligibility criteria:

• Percentage Criteria in X and XII: 85% or 8.5 CGPA
• Pursuing Degree: 90% or 9.0 CGPA
• No Standing Arrears

Round 1: Coding round
Time: 2hr

This was a coding round conducted on the HackerEarth platform. There were 2 coding questions:

• Given a N*M chessboard and each non-empty cell contains either of the three pieces B, R and Q. B can move diagonally, R can move horizontally or vertically, Q can move in any direction in which B and R can move. Find the total number of next valid chess move possible.
• Given a string with lowercase letters and “?” where each “?” can be replaced by any lowercase character, find the total number of strings such that the first and last characters are the same and no adjacent characters are the same.

Round 2: Technical Interview Round-1
Time: 1hr

The interviewer started off by discussing my project. It was just a general talk on what was my project idea and what technologies I had worked upon. After this, the interviewer shifted to DSA questions. He asked me 2 problems:

• Given an array A[] of N numbers and another number K, return the first pair of elements whose sum is exactly equal to K. It was a simple modification of the below problem:
  https://www.geeksforgeeks.org/given-an-array-a-and-a-number-x-check-for-pair-in-a-with-sum-as-x/
• Josephus Problem. I discussed both the recursive approach as well as the optimized approach but he was looking for an approach that involved the use of data structures. After thinking for some time I came up with the Circular Linked List approach. The interviewer was satisfied with this approach and asked me to code it.

Round 3: Technical Interview Round-2
Time: 1hr

The interviewer started off by discussing my internship. Some basic questions on the Agile framework, the challenges I faced during my internship, the technologies I worked on, etc were asked. After this, we shifted to some coding problems:

• Given a string, find the characters which appear exactly once in this string. The interviewer wanted me to solve this problem using a data structure other than a map.
  I came up with an approach using unordered sets. I can maintain 2 sets: appeared exactly once and appearedMoreThanOnce. Now, as soon as I encounter a character, I’ll first check if this character already exists in the appearedMoreThanOnce set: If it exists then I’ll just move to the next character in the string. or Otherwise, I’ll look for this character in the appeared exactly once set. If I find that the character already exists in this set, I’ll remove the character from this set and insert it in the appearedMoreThanOnce set. Otherwise, I’ll insert the character in the appeared exactly once set.
• Find the kth smallest element in an unsorted array. I told her the approach of the Quick select algorithm. After this, I was told to solve this same problem using as many data structures as possible. I then told the interviewer about approaches that involved the following data structures: Linked list, Stack, Queue, Heaps, BST.

Round 4: Technical + HR Interview
Time: 30min

• I was first asked to introduce myself and then given a problem – Count maximum points on the same line. I had come up with O(N^2) in some time but the interviewer expected me to optimize it further. After this, he asked me if I had any questions. I asked him about the work culture in Paypal and how is Paypal competing with other payment services.

I got an offer from Paypal along with 12 other candidates.

Tip:

• If you are given a coding problem, make sure you understand the problem completely. Don’t hesitate to clarify anything about a problem in the interview. Once you are completely sure what the problem is, then try to talk about some base cases/edge cases at the beginning itself. After this, you can start to approach the problem. Also, I feel it’s a good idea to make some test cases and work upon them.