Wex

Role: Java Developer (Technical Screen)

College: Not Specified (Graduated late 1980s)

Interview Date: April 2025 (posted date)

Interview Type: Full-Time

Result: Rejected (implied)

Difficulty: Hard (for the candidate due to focus on algorithms)

Rounds: Technical Screening

Topics Asked: Algorithms, Data Structures, Time Complexity (Big O notation), Hash Maps, Merge Sort

Experience:

A candidate with over 35 years of professional experience as a Java developer encountered a technical screening for WEX. The questions focused heavily on fundamental computer science algorithms and data structures, which the candidate found challenging as their work historically did not rely on such deep algorithmic knowledge. The candidate presumed they would not get the job due to this focus.

Technical Screening Questions:

• Can you explain time complexity, such as Big O notation (for example, O(N)), and why it is important in evaluating algorithms?
• What is the difference between O(N) and O(1) retrieval times? Can you provide examples to illustrate each?
• If an algorithm has a time complexity of O(Log N), what does this imply about its efficiency and how it solves problems?
• Could you explain how a Hash Map functions, including its underlying mechanics?
• How does the merge sort algorithm work, and what is its time complexity?