Classic problem that looks easy until you start coding it.
Clarify the exact matching rules (e.g., bijection between pattern characters and substrings, empty substrings allowed) and edge cases. Then propose a backtracking solution with memoization to efficiently explore possible substring lengths for each pattern character, or a DP approach if the constraints allow. Analyze time and space complexity and discuss potential optimizations.
Pro tip: Demonstrate strong communication by walking through a small example step-by-step before coding, and explicitly state your assumptions about the matching semantics. This shows you think before coding and can align with the interviewer's expectations.
Ask questions to confirm the matching rules: Does each pattern character map to a non-empty substring? Must the mapping be bijective (one-to-one)? Are there constraints on pattern/string length?
Walk through simple examples (e.g., pattern 'ab', string 'redblue') and edge cases (empty pattern/string, repeated pattern characters, no match). This ensures shared understanding.
Explain how to recursively assign substrings to pattern characters, ensuring consistency with previous assignments and using memoization to avoid redundant work.
State the time and space complexity of the backtracking solution (e.g., exponential without memoization, polynomial with memoization). Mention potential DP formulation if applicable.
Implement the solution cleanly, then test with the examples and edge cases discussed. Be prepared to trace through the code.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.