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Wissen Technology for a backend developer role at Flipkart.(12Lpa FIXED)

Round 1: Online Assessment (OA)

Questions:

  1. 6 easy MCQs focused on OOP, mainly interfaces and exception handling.
  2. Two coding questions:
    • Counting letters and finding the first letter with a frequency of 1.
    • Calculating the total number of candles that can be used if K wax is left.
  3. SQL question:
    • Finding all fields greater than a given number.
Candidate's Approach

No approach provided.

Interviewer's Feedback

No feedback provided.


Round 2: Technical Round 1 (R1)

Questions:

  1. Find Majority Element Without Extra Space.
  2. Minimum number of stations required to accommodate all trains.
Candidate's Approach
  • Initial approach: Sort based on Arrival and Departure and count using two pointers (O(n log n)).
  • The interviewer was not satisfied with this solution, so I used the Line Sweep technique:
    • Mark Arrival index with +1 and Departure index with -1.
    • Calculate the Prefix Sum and find the maximum (O(n) time, space O(2401)).
Interviewer's Feedback

No feedback provided.


Round 3: Technical Round 2 (R2)

Questions:

  1. Remove duplicates from Sorted Array without using extra space and replace extra elements with null.
  2. Buy and sell Stock (O(n)).
  3. SQL: Given Student, Subject, and Marks, find Max Marks obtained by Student in descending order.
  4. A CSV file is given; store it somewhere so that we can find an element in O(1) and the previous element also.
Candidate's Approach

No approach provided.

Interviewer's Feedback

No feedback provided.


Round 4: Technical Round 3 (R3)

Questions:

  1. How to remove duplicate files from a folder?
    • First Approach: Using Multithreading to compare all files with the help of threads.
    • Second Approach: Using HashSet and Multithreading to compare all files and store the binary converted to string.
    • Follow Up: How will you handle collision?
  2. How can we prevent a server from being taken down by an IP sending excessive requests, considering the threshold is 100 requests per second per IP?
    • My approach: Create a new section in the database to store request data. If an IP exceeds 100 requests per second, disconnect that IP or use Kafka Rate Limiter.
  3. Implement a retry mechanism in Java that attempts to execute a function multiple times before failing (Assume we are retrying a certain number of times before disconnecting).
    • Function is of generic type. Hint: use Exception handling.
Candidate's Approach

No approach provided.

Interviewer's Feedback

No feedback provided.