core practice · coding problem
Trie prefix membership
Insert ["app","apt","bat"]. Implement startsWith("ap") and search("apt").
The mechanism
A trie stores strings in a tree where each path from the root spells out a prefix. It makes prefix queries (autocomplete, IP routing) take time proportional to the length of the prefix, not the size of the dataset.
Expected evidence
startsWith true; search true; search("ba") true prefix but search("ban") false.Try this drill in the practice workspace →
Hints when you need them
- Each node maps char → child.
- End-of-word flag for complete keys.