Classic word break variant but applied across the whole list, which trips you up if you just think about it as a single string problem.
Use a set for O(1) lookups and for each word, recursively check if it can be segmented into two or more smaller words from the set. Optimize with memoization to avoid redundant computations and handle edge cases like empty strings and duplicates.
Pro tip: Clarify whether a word can be formed by concatenating two or more words, and whether the same word can be reused. Also, discuss trade-offs between recursive memoization and iterative DP, and mention that sorting by length can help process smaller words first.
Ask if words can be reused, if the concatenation must use at least two words, and how to handle duplicates or empty strings. Confirm the expected output format.
Store all words in a hash set for O(1) lookups. Optionally, sort words by length to process shorter words first, which can simplify recursion.
For each word, recursively check if it can be split into a prefix that is a word in the set and a suffix that is either a word or can be further split. Use memoization to cache results for each word.
Write clean code with helper functions. Test with edge cases: no concatenated words, all words concatenated, overlapping words, and large inputs to ensure efficiency.
Discuss time and space complexity. With memoization, time is O(n * L^2) where n is number of words and L is max length, but can be optimized with trie or DP.
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