Arcesium Lead Engineer Interview Experience (Couldn't Clear Round 2)

Round 1 - Online Assessment

Question 1: Expression Evaluator

Given JSON input from an API endpoint containing expression groups, evaluate expressions based on their type:

• DIRECT
• DOLLAR_EXPRESSION
• RS_EXPRESSION

Requirements included:

• Dependency resolution between expressions
• Variable substitution using ${variable}
• Extensible design for future expression types
• Memory-constrained processing (millions of groups, limited groups in memory at a time)

The focus seemed to be on clean design, dependency handling, and scalability.

Round 2 - DSA

Question 1: Decode Numeric String to Letters

Encoding:

A → 1 B → 2 ... Z → 26

Example:

2116

Possible decodings:

• 2,1,1,6
• 21,1,6
• 2,11,6
• 2,1,16
• 21,16

Answer = 5

Essentially a variation of the classic Decode Ways problem.

Question 2: Check Ancestor Relationship in Tree

Given a tree and multiple queries (X, Y), determine whether X is an ancestor of Y.

Example:

1 -> 2 1 -> 3 2 -> 4 2 -> 5 3 -> 6 5 -> 7

Queries:

1 6 => true 6 1 => false 2 7 => true 2 6 => false

Takeaways

• DSA fundamentals are still extremely important even for senior/lead roles.
• Interviewers were interested in both correctness and discussion around complexity.
• Tree traversal and DP-based problems remain common.

I didn't make it through this time, but it was a good learning experience. Hope this helps someone preparing for Arcesium interviews.

Good luck to everyone interviewing!