What is the Implement Trie (Prefix Tree) pattern?

The Implement Trie (Prefix Tree) is a common coding interview pattern in Trie problems. It provides a structured approach to solving related algorithm challenges efficiently.

When should I use Implement Trie (Prefix Tree)?

Use the Implement Trie (Prefix Tree) pattern when you encounter problems matching its characteristics. Check the "When to Use" and "Clues" sections in the lesson for specific indicators.

Is Implement Trie (Prefix Tree) asked in FAANG interviews?

Yes, Implement Trie (Prefix Tree) is an essential pattern commonly tested in FAANG and top tech company technical interviews.

Trie

Medium

Implement Trie (Prefix Tree)

Design a data structure that supports insert, search, and startsWith.

10 min read

Solve on LeetCode

Problem Description

Implement Trie class:

insert(word): Inserts string word.
search(word): Returns true if string word is in the trie.
startsWith(prefix): Returns true if there is a previously inserted string having prefix.

Interactive Visualization

Step 1 / 1

Visualization coming soon...

Initializing...

Custom Input

See the Logic in Motion

Stop memorizing code. Unlock the full interactive visualizer to master the logic step-by-step.

Unlock VisualizerPREMIUM FEATURE

Algorithm Strategy

Node Structure: Each node contains a map/array of size 26 (for 'a'-'z') and a boolean isEnd.
Insert: Traverse down; create nodes if missing. Mark last node as isEnd.
Search: Traverse down; if node missing -> return false. At end, return node.isEnd.
StartsWith: Traverse down; if node missing -> return false. If loop finishes, return true.

Stop Guessing, Start Mastering.

Build the FAANG intuition. Master this pattern with optimized implementations, visual dry runs, and our curated collection of high-yield problems.

Start Your Premium Prep