I stared at the example for longer than I should have.
Clarify the problem constraints (e.g., string length, character set) and edge cases, then propose a greedy algorithm that finds the rightmost position where a character can be incremented to a larger character, and fills the suffix with the smallest possible characters while ensuring no two adjacent characters are equal. Discuss time and space complexity, and consider optimizations like using a priority queue or counting sort for character selection.
Pro tip: Demonstrate Amazon's Leadership Principles by proactively discussing trade-offs between different approaches (e.g., greedy vs. backtracking) and emphasizing customer impact through efficient, scalable solutions. Also, mention testing with edge cases like single-character strings or strings with all identical characters.
Ask questions to confirm the character set (e.g., lowercase letters), input size limits, and expected behavior for edge cases like empty strings or strings with no valid next permutation.
Scan from right to left to find the first position where a character can be increased to a larger character that differs from its left neighbor, then fill the remaining suffix with the smallest possible characters while avoiding adjacent duplicates.
After incrementing, construct the suffix by repeatedly choosing the smallest character that is not equal to the previous character, ensuring lexicographically minimal result.
Discuss time complexity (e.g., O(n * alphabet size) or O(n) with efficient data structures) and space complexity, and propose optimizations like using a frequency array or priority queue.
Walk through examples, including the given one, and test edge cases to ensure correctness. Mention potential pitfalls like infinite loops or incorrect handling of no-solution cases.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.