OLA Interview Experience

Round 1 (around 35 min):
1. Given a matrix containing 0’s and 1’s. Find all the rows which are having 1’s at same position.
Give all sets satisfying this.
2. In a stock market given are price of shares spread over a week. On what day should I buy and what day should i sell to get maximum profit.
3. Being a computer engineer why did I not opt for system side programming than web domain. (I had expr in web domain)
4. I had expr in web domain so he asked : What is difference between web browser request and ajax call request.
— It is simple , by ajax call partial web page can be loaded.
5. Have you worked on ruby on rails?

Round 2 :
1. Given a matrix containing numbers. Find the 0’s and make all the rows and columns corresponding to that index as 0.
2. Design a structure for a File Uploader service (eg. Dropbox , google drive) . It is a service where multiple person can upload
data at same time and it also lists the top five uploaders (who uploaded maximum number of files).
3. Puzzle : There is a employer and a worker ,employer has gold bar of 7 units and he has to give 1unit each on a day for 7 days.
Employer has a magical knife which doen’t works once it performs two cuts(1 cut divides bar into two parts) on bar.
How will you cut so that 1 unit on each day can be given to worker.
4. Print left view of binary tree.

Round 3 :
1. He discussed about what things they work on Ola. How these things are implemented. Like he mentioned of bar code a product has and catlaog kind of thing.
2. I had to explain what project I am working on currently, what is the team size.
3. a)Since I had worked on Sql and databases, so he asked me what data structure will i use to implemet a database.
–I gave hashmap as a soln (key is our primary key and other fields we can store in object which will be value for hashmap)
b)Now, If in case you want to find all names starting with particular word (eg. ram….).How will you do that.
— gave trie structure as soln.
c)Now you need to find students whose marks are between a range i.e. between two numbers. How will you do, what data structure will you take in this case.
— a simple slon was that, take binary search tree and do inorder traversal of that (I coulnd’t answer this, not clicked me)
4. Do you want to ask anything.

Round 4 :
1. Server receives a ping every 30 secs. The ping is load avg on the machine at that time. Find 90% percentile of the load average on the machine
at any time instant.
2. Find missing number in an AP.

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