← Capital One Interview Insights
Not hard but I second-guessed the case-insensitive part for a second and almost forgot to lowercase before comparing.
Clarify the problem constraints (e.g., string length, character set) and confirm edge cases. Then describe a linear scan using a sliding window of size 3, comparing the first and last characters case-insensitively. Finally, analyze time and space complexity and discuss potential optimizations or variations.
Pro tip: Mention that you would handle case-insensitivity by normalizing characters (e.g., using toLowerCase) before comparison, and explicitly state that the window slides by one character to avoid redundant checks. This shows attention to detail and efficiency.
Ask about input size, character set, and whether overlapping windows should be considered. Confirm that the count increments only when the first and last characters match case-insensitively.
Explain that you will iterate through the string with a window of size 3, comparing the characters at the current index and index+2 after converting both to the same case. Increment a counter when they match.
Choose a short string (e.g., 'AbcA') and manually demonstrate how the windows are formed and which ones count, ensuring the interviewer follows your logic.
State that the time complexity is O(n) where n is the string length, as each character is visited a constant number of times, and space complexity is O(1) since only a counter is used.
Mention that the solution is already optimal for a single pass, but you could discuss handling Unicode or using a two-pointer approach if the window size were larger.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.