# Flipkart Interview Experience | Set 17 (For SDE II)

• Difficulty Level : Hard
• Last Updated : 27 May, 2019

I was interviewed for SDE – II position @ Flipkart. Below is my experience.

• Round 1 : Telephonic Round (around 90 minutes)
He started with his and my introduction, the products I have worked on, the challenges I have faced during its development ( basic questions). Then he asked me 2 questions.

1. Find the LCA (least common ancestor of 2 nodes) in a Binary Tree
node structure – > data, left child, right child, parent.

2. Design a data structure which would allow you to perform the following 2 operations supported in O(1) complexity.
a. Insert an element.
b. Return a random number from the numbers inserted so far. A random function is given which generates a random number.
c. Delete(int num) finds and delete a number from the ones inserted so far.
• Round 2 : Machine Coding round. ( 90 – 120 minutes)

The full working code was required. They gave us more than 2 hours to complete.

Discussion on the code written and how i have implemented.

• Round 3 : Problem Solving Round ( 45 – 60 minutes)
1. Level order Traversal of a Binary Tree.
2. You are given a string of 0’s and 1’s you have to find the number of substrings in the string which starts and end with a 1.
eg : input : 0010110010
output : 6

3. You are given a mapping like a → 1, b → 2, z → 26.
You have to print all possible combinations of a given number using the above information.
eg : input : 121
output : aba,la,au

4. String Compression Algorithm.
You have to compress a string in the following format.
eg : input : aasasatb
output : 2a2sa1t1b
• Round 4 : Hiring Manager (40 minutes)

General talk around what they do and what they expect from an engineer.

Gave me a puzzle : You intend to fly non-stop around the world. But a full tank only takes you halfway around the world. However you can arrange many planes exactly like yours to assist with refueling. You can only use the starting airport, and refueling can be done midair.
Ignoring refueling and turn-around times, what is the minimum number of planes you will need?<

I would like to thank GeeksForGeeks for helping me in the preperation, i dont know the result so far but am very content with my overall experience during the interview.

Thanks and best of luck to all other geeks.

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