Implement Trie (Prefix Tree)
Implement a trie (prefix tree) for efficient string storage and retrieval. Think about: How to represent the tree structure? Hint: Each node should track its children and whether it marks a word end. Example: insert("apple") search("apple") → True search("app") → False starts_with("app") → True
Implement Trie (Prefix Tree) is a tree problem that rewards clean recursion and a crisp definition of what each call returns. Interviewers love it because it reveals your recursive thinking and your edge-case discipline. Once your recursion contract is clear, the implementation becomes almost mechanical.
Meet Coco
Coco is an AI study partner, not a person. She listens while you explain your code, asks what a line does and never hands you the fix. Typing with Coco is free when you sign in, up to a daily limit. Talking with her out loud comes with the $79 pack. Anyone can open the editor and run their code.