Recently appeared for GreyOrange SDE3 interviews. Sharing questions for others preparing for backend/system design roles.

Coding Round Questions:

1. Design a backend data model for a social media platform supporting comments and comment likes at scale.

Requirements:

• Fast comment retrieval
• Efficient like tracking
• No duplicate likes
• Handle large scale traffic/data

2. String parsing/compression problem

Examples:
a1b2c3

a11b2 -> 13

(Parse/decode/compress string with character-frequency handling and multi-digit counts.)

3. Sliding Window Problem

Given a string and a keyword, find the shortest substring containing all characters of the keyword.

Example:

Input:
ADOBECODEBANC
ABC

Output:
BANC

Length = 4

4. Design a data structure supporting:

• Insert(value)
• Delete(value)
• GetRandom()

All operations should work in O(1).

5. Production Deployment Scenario

During a critical production deployment, an issue occurs after release.

Explain:

• How you communicate the issue
• Business impact
• Mitigation plan
• Next steps

System Design Round:

1. Design an automated circular parking lot system
Requirements:

• Multiple entry gates

• RC scan at entry

• Circular parking lot

• Parking + exit operations

• Billing:

  • ₹100 for first hour
  • ₹40/hour afterwards

• Each level can support only 3 concurrent operations

• Concurrency handling discussion

2. Design warehouse robot/task orchestration system
Topics discussed:

• Task allocation
• Robot coordination
• Real-time updates
• Failure handling
• Queue/message broker usage
• Scalability

Could not clear the system design round, but overall discussion was interesting and focused heavily on concurrency, scalability, and real-world backend design.