I applied to OLA through referral for the position of SDE1.
Round 1 (F2F Virtual Interview): 4 DS Algo questions(codepair round on hackerrank).
- Reverse an array.
- Rain Water Trapping problem.
- Minimum time needed to burn a tree starting from a node.
- Minimum cost for joining ropes of different length. (Follow up:Implement your own heap).
Round 2(F2F Virtual Interview): 3 DS Algo questions(share screen and code) .
- Generate all permutation of a string.
- Generate all distinct permutations of a string.
- Generate next smallest permutation of a number. – Similar problem
Round 3(F2F Virtual Interview): 2 DS Algo questions(share screen and code).
- Given a n*m grid of different characters, check if a cycle of size greater than three exists.(cycle must contain similar characters, consider left right up bottom character as neighbour)
- Product of Array Except Self.
Round 4(F2F Hiring Manager round):
- Introduce yourself.
- Questions related to my project.
- Questions on scaling(Vertical scaling vs horizontal scaling).
- Questions on SQL vs NOSQL.
- Types of HTTPs method.
- Difference between PUT and POST.
- How would you search all the numbers common in a small file and a big file.
- What DS would you use while creating your own hashing algorithm.
- Some behavioural questions.
For all DSA question they asked to explain the approach first and then code. In between lot of cross question was asked.