The interview lasted 45 minutes, and the interviewer was super supportive. You just need to keep them in the loop with your approach, and they will always try to help you move forward.

Questions Asked

The questions were simple and based on range-based counting frequency. For example:
• Problem Statement: Increase the frequency from l to r.
• Queries: There are q queries, and at the end, return the frequency of every index.

My Approach

1. Started with brute force, then we discussed its time complexity.
2. Implemented the brute force approach.
3. The interviewer then asked me to optimize it.
4. I optimized it using prefix sum.

Follow-up Questions

1. Find at which query the frequency of every number from 1 to n is greater than 0.
   this I did using Binary search

Our disucssion ends in 40 minutes and in the last 5 minutes we discussed about his work experince at google.

I got positive response from hr and moved to onsite rounds.
Thank You
Similar question: https://leetcode.com/problems/zero-array-transformation-ii/description/?envType=daily-question&envId=2025-03-13