Walmart Interview Experience:
Round 1 (DSA):
3 DSA question:

1. N meetings 1 room (GFG)
2. Minimum Platforms Required (GFG)
3. Merge Intervals | https://leetcode.com/problems/merge-intervals/description/

Round 2 (Same Day): Java + LLD

1. Aggregation, Composition, is-a relation, has-a relation
2. New features in Java 8 (As I'm working on Java 8)
3. Design Patterns using in daily life (I said singleton, builder, Observer, Factory)
4. Coded Singleton patter. Questions on that:
   • why making instance as static?
   • is static required
   • use of static
   • How to make sure that getInstance class is thread safe
     Ans: using synchronized block/ function
5. Code Observer Design Pattern
   • How the updated attribute is communicated to all observers
6. Volatile keyword
   • Use
   • Memory Aspect
7. No. of ways you can acheive multithreading in Java
   Ans: -Implement runnable interface
   -Extend Thread class
   -Executor Service
8. Marker Interface

Round 3 (HM round -> After 5 days)

1. Discussions on projects
2. Biggest Technical challenge in one of the projects
3. Design a System to migrate 100,000 rows from 1 DB to Another
   • For single instance
   • For multiple insatnce (how to make sure reading of old DB is safe and no record is read twice)
     Ans: SQL Locks
     Funtional Requirements
   • No duplicate rows in new DB
   • No data loss between two DBs
   • No new table should be created. You are free to modify the old table
     More Behavioural questions

Verdict: Selected