I started with the split-on-dot approach and immediately ran into the leading zeros edge case, which I nearly missed.
Clarify the exact validation rules and edge cases, then propose a clean solution that splits each string by dots and validates each octet. Discuss trade-offs between regex and manual parsing, and consider performance for large arrays.
Pro tip: Mention that you would avoid regex for performance-critical code and instead use a manual parser, but note that regex is acceptable for readability if performance is not a concern. Also, highlight the importance of handling edge cases like empty strings and leading zeros.
Confirm the definition of a valid IPv4 address, including rules for leading zeros, empty octets, and non-digit characters. Ask about input constraints (e.g., array size, string length) to guide optimization.
Decide between using a regular expression or manual parsing. Discuss the trade-offs: regex is concise but may be slower and harder to debug; manual parsing is more verbose but faster and more controllable.
For each string, split by '.', check that there are exactly four parts, and validate each part: non-empty, only digits, no leading zeros (unless the part is '0'), and numeric value between 0 and 255.
Walk through examples: valid addresses like '192.168.0.1', invalid ones like '256.1.1.1', '1.1.1', '1.1.1.1.1', '01.1.1.1', and empty strings. Ensure the function returns false for any invalid string.
State that the time complexity is O(n*m) where n is the number of strings and m is the average string length. Mention that early termination (returning false as soon as an invalid string is found) can improve average-case performance.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.
First, clarify the exact formats for IPv4 and IPv6, including edge cases like leading zeros and compressed notation. Then, design a modular solution with separate validation functions for each IP version, and finally combine them to classify the input. Discuss trade-offs between regex and manual parsing, and consider using built-in libraries for robustness.
Pro tip: Mention that you would use a well-tested library like Python's ipaddress module in production, but implement the parsing manually in an interview to demonstrate understanding. This shows you value both correctness and practical engineering.
Ask the interviewer about the exact definition of valid IPv4 and IPv6 addresses, including whether leading zeros are allowed, how to handle compressed IPv6 notation, and if IPv4-mapped IPv6 addresses should be considered IPv6.
Outline separate functions for validating IPv4 and IPv6, each returning a boolean. This separation simplifies testing and maintenance, and allows easy extension to other formats.
Split the string by dots, ensure exactly four parts, each part is a number between 0 and 255, and no leading zeros unless the part is '0'. Consider using a regex or manual parsing.
Handle the full and compressed forms: split by colons, allow '::' to represent one or more groups of zeros, ensure each group is 1-4 hexadecimal digits, and the total number of groups (including compressed) equals 8. Optionally, handle IPv4-mapped addresses.
Call both validators and return 'IPv4' if the IPv4 validator passes, 'IPv6' if the IPv6 validator passes, and 'Neither' otherwise. Discuss potential ambiguities and how to resolve them.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.