The greedy part clicked pretty fast but I initially forgot to handle the 'no match' case properly and was just skipping characters instead of appending them.
Clarify the problem constraints and edge cases, then propose a greedy left-to-right algorithm using a trie for efficient longest-prefix matching. Discuss time/space complexity and potential optimizations, and walk through an example to validate correctness.
Pro tip: Mention that a trie can be built once and reused for multiple strings, and that if the dictionary is small, a simple loop over tokens sorted by length might be sufficient—showing you consider trade-offs.
Ask about input size, dictionary size, token length limits, and expected output format. Discuss handling of overlapping tokens, empty strings, and non-matching characters.
Propose a greedy left-to-right scan. At each position, find the longest dictionary token that matches the current prefix. If found, append its ID and advance by token length; else append the character and advance by one.
Use a trie (prefix tree) to store dictionary tokens for O(L) lookup per position, where L is the max token length. Alternatively, if the dictionary is small, sort tokens by length and check each.
Time: O(N * L) with trie, where N is string length and L is max token length. Space: O(D * L) for trie, D = number of tokens. Discuss trade-offs vs. naive approach.
Walk through a sample string, including cases with overlapping tokens, no matches, and tokens at the end. Verify correctness and performance.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.