Look for these signals in the problem:
- "Prefix" search or autocomplete: Trie finds all words with given prefix efficiently.
- "Word dictionary" with insert/search: Trie handles both operations in time.
- "Wildcard" matching (like '.'): Trie enables DFS exploration at wildcard positions.
- "Word search" in grid with dictionary: Trie prunes paths not matching any word prefix.
- "Longest common prefix": Traverse trie until branching to find shared prefix. Uses space.