Flipkart Interview | Set 3

Recently I appeared for Flipkart Interview. I would like to share my experience. 

Round-1: Telephonic (45 mins)

1. Given an array of n distinct integers sorted in ascending order. Find an index i s.t ar[i] = i. Return -1 if no such index exists. Note that integers in array can be negative. 
   Article Link: https://www.geeksforgeeks.org/find-a-fixed-point-in-a-given-array/
   Practice Link: https://practice.geeksforgeeks.org/problems/value-equal-to-index-value1330/1
   
2. Design a stack which holds an integer value such that getMinimum() function should return the minimum element in the stack. 
   FOLLOW UP: Implement popMin() function which would pop minimum element from the original stack. O(1) implementation was required. (Hint: Use LinkedList to implement stack and store address of minimum element node in min-stack) 
   Article Link: https://www.geeksforgeeks.org/design-a-stack-that-supports-getmin-in-o1-time-and-o1-extra-space/
   Practice Link: https://practice.geeksforgeeks.org/problems/special-stack/1
   
3. Print an organisational hierarchy. 
   Naveen manages Satish 
   Satish manages Anushree 
   Satish manages Sandeep 
   Gurinder manages Naveen 

   Gurinder->Naveen 
   Naveen->Satish 
   Satish->Anushree,Sandeep 
   Anushree-> 
   Sandeep->

Round-2: Telephonic (30 mins) 

• Given an array which is first strictly increasing and then strictly decreasing. Find an element in this array. Discussions on various approaches and their complexities.
  Article Link: https://www.geeksforgeeks.org/find-element-bitonic-array/
  Practice Link: https://practice.geeksforgeeks.org/problems/maximum-value-in-a-bitonic-array3001/1

Round-3: In-House Coding(1 Hour 45 mins)
Write a running code in any language to implement the famous tic-tac-toe game. 
First, there was a discussion on various approaches and basic functions which would be required to implement the same. Then I was asked to code. 
I was given 1 hour 15 mins to code this. I had to design this game as per following: 

• Game has 3 modes: Human Vs Human, Human Vs Computer and Computer Vs Computer. 
• Initially start with a 3X3 grid, but it can be generalised to NXN grid. So don’t hardcode any variable. 
• Minimise Code Redundancy and try to make it as modular as possible. 
• Try to use abstraction and expose a lesser number of functions(APIs) to the outside world. 
• Try to cover maximum number of edge cases, like when to abort the game, draw condition, win condition, overwriting the existing value in grid etc)

Round-4: Data Structure and Problem Solving(1 Hour)

1. Given a sorted and rotated array. Find an element in this array. (Famous Problem) 
2. This was an interesting problem. Given a set of intervals like 5-10, 15-20, 25-40, 30-45, 50-100. Find the ith smallest number in these intervals. 
   Assume there are no duplicate numbers.

   e.g:  1st smallest number = 5
         6th smallest number = 10
         7th smallest number = 15 and so on. 

   I told him that we would first sort the interval on basis of starting numbers. Then merge overlapping intervals to get a set of non-overlapping intervals like 5-10, 15-20, 25-45, 50-100. Now we can find the ith smallest number after finding the appropriate interval. 

   FOLLOW UP: He then modified this question to accommodate duplicate numbers also.

   Suppose we have intervals like 5-10, 8-12. 
   Then total numbers in these two intervals would be: {5,6,7,8,8,9,9,10,10,11,12} 
           So, 1st smallest number: 5
               4th smallest number: 8
               5th smallest number: 8 (here is the 
   change since now we have duplicate elements also) and so on. 
   

3. Given a dictionary of 50,000 words. Given a phrase without spaces, add spaces to make it a proper sentence.

   e.g: input:  thequickbrownfoxjumpoverlazydog
       output: the quick brown fox jump over lazy dog

FOLLOW UP Questions: 

1. Worst case complexity of finding a word in HASHMAP given we have ‘B’ buckets and total of 50,000 words. ( Ans: O(50,000/B) ) 
2. Complexity of finding a word in TRIE. (Ans: O(Word Length) ) 
3. Advantages of TRIE over HASHMAP and some similar discussion.

Round-5: Hiring Manager Round(45 mins)
He asked me lots of questions regarding my current company projects. 
Questions: 

1. My role in current project. 
   
2. Most Challenging work in your company. 
   
3. What technologies you learnt last year? and several similar questions.

Round-6: HR Round (10 mins)

• Common HR questions like why Flipkart, Why should we hire you etc.

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All Practice Problems for Flipkart !