Share character-by-character paths so every node represents a prefix and can retain information about words with that prefix.
THE MENTAL MODEL
When should this come to mind?
Share character-by-character paths so every node represents a prefix and can retain information about words with that prefix.
Prefix lookupAutocompleteShared string prefixes
What makes it work
Define the alphabet, duplicate-word behavior, and empty-prefix behavior. An exact-word query needs terminal markers; prefix counts instead store words passing through each node.
When to choose something else
Exact membership alone may be simpler with a hash set; tries can use substantial memory for sparse keys.
See the pattern in action
Change the input. Follow the state. Make it yours.