Quikr Interview Experience | Set 3

Round -1 on hacker rank
1) Find the first repeating word in a sentence.
– Use a set to store word by word and insert would return false when it is duplicate.
– Use a hashmap to store the counts and detect the duplicates.
2) Given a list of coordinates what is the minimum size of the rectangle so that k number of points lies inside the rectangle.
– Could not find completely correct answer solution written only passed 6 test cases.

Round – 2
1) Print path to a node from root in a binary tree.
– Easy question asked to write the code and checking if we cover the edge cases.
2) Find the median of continuous stream of numbers.
– More frequently asked in amazon interview questions
3) Delete a node in a linked when you have nothing other than the pointer to the node you want to delete.
– Traversing to find the node we want to delete is not a viable approach, could get the idea of copying from the next node and as we prev pointer to the node we want to delete it’s good.
– Edge case what if the node is last node of the linked list.
4) Data structure to pick to store the words of a dictionary.
– Hash maps are not the optimal solution as you end up allocating memory for each word.
– Tries are the best possible data structures to pick
5) How tries are better option than the Hash Maps for storing the words of a dictionary?
6) Load factor of hash map and how does it affect the performance of the hash map.
7) Asked questions on equals and hash code contract of the hash maps.
8) Times when you decide to pick a linked list or Array List.
– When you requirements is you perform more number of deletes and insertions rather than the search.
9) Asked the difference between concurrent hash maps and Collections.synchronized(hashmap)
– Fumbled a bit as i was not aware of the lock striping that happens in the conccurent hashmaps.
10) Explain on fail fast and fail safe iterators.
11) is static overriding allowed if not why ?
– Not possible as static methods are binded at compile time and nonstatic methods are binded at the run time.
12) Asked about thread pools and why use them ?

Round – 3
1) Asked me to write the code for the deadlock creation
– Wrote 2 runnables where they call nested synchronized locks in the reverse order/
2) how to prevent dead locks ?
3) Asked some question related to threading
4) Given list of words of a dictionary {cat, rat, mat,map} given 2 words cap – map
you can change only one character at a time
eg: cap – cat – mat – map
“http://paste.ofcode.org/6Cb2DFbwHXB2nG3xJEze2n” – code logic i suggested.
5) Questions on sharing objects using serialization.Also spoke of using gson to Json utility for sharing objects across applications

Round – 4
1) Asked me to write code for the singleton pattern
– Wrote code for the doubly checked singleton pattern
2) Asked me if i know decorator pattern
– I said i had no idea of it.
3) Asked me on Robot capable of moving in different directions but it should have the capability to make the steps back
– It didnt click stack is the data structure i should use, Interviewer gave the hint of stack.which is the appropriate data structure to make the steps back.
4) Asked a small question on if there are other objects which cannot be serialized that we have to use in our class which is expected to
be serializable how do we do it ?

Round – 5 (F2F)

1) Asked questions on Message queues, How did you perform request response implementation using the message queues ?
2) What is JMS how is it different from other tool vendors like active mq and so on ?
3) Asked significance of queues and topics.
4) Given a list of users and their phone numbers each user can have multiple number of phone numbers
How to get the m users having highest number of phone numbers
– Data storage structure suggested was HashMap>?
– Interviewer gave me hint that i can get the entry map as list with in the hashmap
– So i wrote a comparator to compare the sizes of the arraylist in the entry map object.
– Called collections.sort();
5) Asked to print the right side view of a binary tree.
– Suggested to do a breadth first traversal on binary tree using queue and pull the last element.
– He asked how will you find the last element of the queue ??
– He suggested how about using stack to perform the breadth first traversal of the binary tree.
6) Asked on how do you get the thread dumps
– said i use jstack command line tool to get the dumps.

Round -6 (F2F)
1) Robot is some where inside the rectangle,it can do only operations such as move forward,backward,left and right.
Asked to find the area of the rectangle.
2) After that he said the rectangle inside is filled with the obstacles of arbitrary size so now how to find the area.
said assuming my rectangle can be broken into smallest units called pixels if i could what all pixels robot can cover i can get the area.
But could not write the code on how to do it.
He said this is similar to breadth first search that we do on a graph connected by points.
But it didnot click.
3) Asked on how to make applications scalable using redis.

I said i had no idea of it.

Source: http://pavanraj84.blogspot.in/2015/08/my-interview-questions-at-quickr.html