What is the Prefix Matching pattern?

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

When should I use Prefix Matching?

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

Is Prefix Matching asked in FAANG interviews?

Yes, Prefix Matching is an essential pattern commonly tested in FAANG and top tech company technical interviews.

Trie

Medium

Prefix Matching

Use Trie to efficiently find all keys matching a prefix.

10 min read

Problem Understanding

This is essentially startsWith but often implies retrieving related data or completing the word. In this lesson, we use the standard startsWith logic as the core building block for Autocomplete systems.

Algorithm Strategy

Start at the Trie root.
Iterate through each character of the prefix.
Check if the current node has a child for that character.
If No: Prefix doesn't exist. Return False.
If Yes: Move to that child node.
If loop completes: The path exists. Return True (unlike Search, we ignore isEnd).

Interactive Visualization

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Custom Input

Prefix

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