I recently interviewed for the Lead Engineer position at Arcesium and wanted to share my experience.

Unfortunately, I couldn't clear Round 2, but I hope the questions help others preparing for similar roles.

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.

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!

#interview #arcesium #leetcode #softwareengineering #dsa #systemdesign