How I Got the Interview Opportunity? 🎯

🖥️ Online Assessment Round

Problems Asked:

1. Count ways to exit matrix [N][M] (4 adjacent directions movements) from given (Sx, Sy) starting point in at most K steps.
   → Solvable in O(N * M * K) using DP
2. You can increment any A[i] by 1 (at most K times), find the maximum frequency of any A[i] possible.
   → Available on LeetCode. Solvable in O(N log N)
   → Approach: Sort Array. Fix L, find best R using binary search (prefix sums required).
3. Game Theory Problem: Given A and C, start with value A! (A factorial). Each player removes B (B ≤ A!) and B should have at most C distinct prime factors.
   • A, C ≤ 10^6
   • Answer: Count unique factors of A! If it is ≤ C, first wins else second wins
4. A Hard problem on Tree (not understandable, and no one solved it).

🔹 First Technical Interview Round (1 Hour Long)

DSA Questions Asked:

1. Find the missing number in a sorted array of size N-1 (consisting of all numbers from 1 to N).
   • My Solution: Expected O(log N) → Binary Search ✅ (Very Easy Problem)
2. Pick K elements from either the start or end of the array such that their sum is maximum.
   • My Solution: Iterate on count of prefix elements from 0 to K and take suffix elements accordingly.
   • Expected Time Complexity: O(N) ✅ (Easy Problem)
3. Query Problem: Given an array of integers, answer queries of type L R D — Count numbers from L to R where the number of digits in that number ≥ D.
   • My Solution: O(N log N) precomputation & O(1) query. Used 2D prefix sum array. ✅ (Medium Problem)

🔹 Second Technical Interview Round (1 Hour Long)

1. Covid Spread in a Binary Tree
   • Given a Binary Tree where nodes are people, the deepest leaf node gets Covid+ first, and the virus spreads to neighboring nodes in 1 sec. Find total time to spread in the whole tree.
   • My Solution: The answer is the Diameter of the Binary Tree (one of the farthest nodes is the first Covid+ node).
   • Time Complexity: O(N) ✅
2. Evaluate a mathematical expression containing brackets, operators, and numbers.
   • My Solution: Used Two Stacks (one for operands & brackets, one for numbers).
   • Time Complexity: O(N) ✅

🔹 Third HR Interview Round (1 Hour Long)

Questions Asked:

• Internships Discussion:
  • Hackerearth: What topics do you usually set problems on?
  • Vicevio (Flutter Internship): How did you improve the architecture & contributions?
• Have you developed any Android App that solved a daily life problem?

🎉 Result: I GOT SELECTED! 🎉

🔥 Some Tips:

• OA Round was Hard 💻 but Interview Rounds were Easy-Medium (mostly Leetcode-style questions).
• Keep interacting with the Interviewer instead of staying silent while thinking.
• Explain easy problems well—most candidates will solve them, but good explanation can make a difference.
• If you don’t know an answer, admit it early rather than diving in blindly.