Yeah this is exactly as simple as it sounds.
Start by clarifying the problem: confirm whether the function should handle null inputs, empty strings, or other edge cases. Then present a simple solution, such as using the language's built-in string concatenation operator, and discuss its time and space complexity. Finally, mention potential optimizations or alternative approaches, like using StringBuilder in Java for multiple concatenations, but emphasize that for two strings, the simple approach is optimal.
Pro tip: Demonstrate awareness of the underlying implementation: in many languages, string concatenation creates a new string, which is O(n+m) time and space. Mentioning this shows you understand performance implications beyond just writing the code.
Ask about input constraints: can strings be null? Are they mutable? What encoding? This shows attention to detail and avoids assumptions.
Write or describe a function that uses the language's concatenation operator (e.g., + in Java, + or += in Python) to join the two strings.
Explain that the time and space complexity is O(n + m), where n and m are the lengths of the input strings, because a new string of combined length is created.
Mention handling of null inputs (e.g., throw IllegalArgumentException or return the non-null string) and empty strings, and how the solution behaves.
For two strings, the simple approach is best. For multiple concatenations, suggest using a StringBuilder (Java) or join (Python) to avoid O(n^2) performance.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.