Trie
Domain: Data Structures
🎯 Motivation
When you need to store and search strings by prefix — autocomplete, spell check, IP routing — a trie organises characters level by level.
📋 Concrete Example
Trie for cat and car: root -> c -> a -> t (end) and c -> a -> r (end). Sharing the ca prefix saves space and enables prefix search.
🔗 Analogy
A library catalogue organised letter by letter. All books starting with C are in one section, CA in a subsection, CAT in a sub-subsection. Finding all books starting with CA is instant.