Hackernoon how to implement trie (prefix tree) – blind 75 leetcode questions

Hackernoon how to implement trie (prefix tree) – blind 75 leetcode questions

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Hackernoon how to implement trie (prefix tree) – blind 75 leetcode questions

In the realm of competitive coding, mastering data structures and algorithms is paramount. LeetCode’s Blind 75, a curated list of commonly asked interview questions, poses a significant challenge for many aspiring software engineers. However, with the right approach and understanding, you can navigate these questions with confidence and finesse. One powerful tool in your arsenal is the Trie, also known as a prefix tree.

Understanding the Trie Data Structure

At its core, a Trie is a tree-like data structure used to store a dynamic set of strings. Unlike traditional tree structures, where each node represents a single character, Trie nodes represent the characters of a string’s key. This characteristic makes Tries particularly efficient for tasks involving string manipulation and search operations.

Structure of a Trie

In a Trie, each node typically consists of the following components:

  • Node Value: Represents a character in the string.
  • Children: Pointers to child nodes, each corresponding to a unique character.
  • End of Word Marker: Indicates the end of a valid word, useful for search operations.

Applications of Tries

Tries find applications in various domains, including:

  • Autocomplete Systems: Tries facilitate efficient prefix matching, making them ideal for autocomplete functionality.
  • Spell Checkers: By storing a dictionary of words in a Trie, spell checkers can quickly identify misspelled words and suggest corrections.
  • IP Routing: Tries are used in IP routing tables for fast lookup operations.

Navigating LeetCode’s Blind 75 with Trie

Now, let’s delve into how you can leverage Trie to tackle LeetCode’s Blind 75 questions effectively.

1. Word Search II

One popular problem from LeetCode’s Blind 75 is Word Search II. Given a 2D board of characters and a list of words, your task is to find all words from the list that can be formed by traversing adjacent cells in the board. Trie’s efficiency in prefix matching makes it an excellent choice for solving this problem. By constructing a Trie using the given list of words and performing depth-first search (DFS) on the board, you can efficiently identify valid words.

2. Palindrome Pairs

Another challenging problem is Palindrome Pairs, where you’re tasked with finding all unique word pairs in a given list such that concatenating them forms a palindrome. Trie can aid in optimizing the solution by storing reversed versions of words in addition to their original forms. This allows for efficient prefix matching and palindrome checks during traversal, significantly reducing the time complexity of the solution.

Tips for Trie Implementation

To maximize your success in conquering LeetCode’s Blind 75 using Trie, consider the following tips:

  • Efficient Trie Construction: Pay close attention to the Trie construction process, ensuring that it captures all necessary prefixes and words from the input.
  • Optimized Search Operations: Implement search operations efficiently, leveraging Trie’s prefix matching capabilities to minimize search time.
  • Memory Optimization: Consider memory optimization techniques such as node compression to reduce the memory footprint of the Trie, especially for large datasets.
  • Edge Cases Handling: Be thorough in handling edge cases, ensuring that your Trie implementation behaves correctly for various input scenarios.
  • Testing and Debugging: Test your Trie implementation rigorously with diverse inputs and debug any issues promptly to ensure its correctness and efficiency.


In conclusion, Trie is a powerful data structure that can significantly enhance your ability to conquer LeetCode’s Blind 75 challenges. By understanding its principles, applications, and implementation strategies, you can pave your path to success in competitive coding interviews and beyond. So, equip yourself with the knowledge and skills needed to harness the full potential of Trie and propel yourself ahead in your coding journey. With Trie by your side, conquering LeetCode’s Blind 75 is well within your reach.

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