Tries mind map
Prefix trees for autocomplete and word search.
Core idea: When many strings share prefixes, store the prefix once as a path.
Mnemonic: Share prefix → descend → mark · Cost: O(L) per word · prefix memory
Build: Insert & exact lookup
Signal: Many repeated word and prefix queries share starting characters.
Move: Descend or create one child per character; a terminal flag separates word from prefix.
Examples: Implement Trie, Prefix Search, Replace Words
Branch: Wildcard search
Signal: One query character can match several stored edges.
Move: Follow one child for literals; fan out only at the wildcard and stop dead prefixes early.
Examples: Word Dictionary, Regex Prefix Match, Magic Dictionary
Walk: Grid + trie
Signal: A board contains many target words with shared prefixes.
Move: Advance board DFS and trie state together; prune once no live prefix remains.
Examples: Word Search II, Boggle, Prefix Pruning
Augment: Prefix metadata
Signal: Queries need counts, scores, or best suggestions at every prefix.
Move: Aggregate metadata while inserting so lookup answers directly at the final prefix node.
Examples: Prefix Scores, Autocomplete, Search Suggestions