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 programming, LeetCode’s Blind 75 represents a formidable challenge for aspiring coders. Among the plethora of data structures and algorithms at their disposal, understanding and implementing the Trie data structure can significantly enhance one’s ability to tackle these problems efficiently. This article delves into the intricacies of Trie implementation and offers strategic insights to empower you in mastering the Blind 75 on LeetCode.

Understanding Tries

Trie, also known as a prefix tree, is a tree-like data structure used to store a dynamic set of strings where the keys are usually strings. Unlike other data structures like arrays or linked lists, which store elements sequentially, Tries provide a more efficient way to search for strings with common prefixes.

Trie Structure

At the root of the Trie is an empty node, representing the empty string. Each subsequent level of the Trie corresponds to a single character of the alphabet. The nodes along the path from the root to a particular node represent the characters that form a string.

Trie Implementation Tactics

Mastering Trie implementation is pivotal in conquering the LeetCode Blind 75 challenges. Here are some tactics to unlock the potential of Trie in solving these problems effectively:

1. Node Representation

When implementing a Trie, each node typically contains an array or a hashmap to store references to its child nodes. This allows for efficient retrieval of characters and traversal through the Trie.

2. Insertion Operation
  • To insert a string into the Trie, start from the root and iterate through each character of the string.
  • Check if the current character exists as a child node. If not, create a new node and add it as a child.
  • Continue this process until all characters are inserted, marking the last node as the end of a word.
3. Search Operation
  • Searching for a string in a Trie involves traversing the Trie following the characters of the target string.
  • If at any point, a character is not found or the traversal reaches a null reference, the string is not present in the Trie.
4. Deletion Operation
  • Deleting a string from a Trie requires traversing the Trie to find the string.
  • Once the string is found, mark the last node as non-terminal to indicate the end of the word.
  • If the deleted node has no other children, remove it from its parent node.

Trie Optimization Techniques

Efficiency is key when tackling LeetCode Blind 75 challenges. Here are some optimization techniques to enhance the performance of Trie implementations:

1. Compressed Tries
  • Compressing Tries can significantly reduce memory consumption by merging nodes with a single child into a single node.
2. Trie Pruning
  • Pruning involves removing branches of the Trie that do not lead to any valid words. This optimization minimizes unnecessary traversal, improving search and insertion operations.

Application of Tries in LeetCode Blind 75

Tries offer a powerful approach to solving a variety of problems featured in the LeetCode Blind 75 list. Here are some common scenarios where Trie implementation shines:

1. Word Search
  • Trie is instrumental in efficiently searching for words in a grid of characters, a problem frequently encountered in LeetCode challenges.
2. Autocomplete
  • Implementing autocomplete functionality relies on Trie to efficiently retrieve suggestions based on user input.
3. Longest Common Prefix
  • Trie facilitates finding the longest common prefix among a set of strings, a problem often encountered in coding interviews.


In the competitive landscape of LeetCode Blind 75 challenges, a solid understanding of Trie implementation can be the differentiating factor between success and stagnation. By mastering the tactics and optimization techniques discussed in this article, you are equipped to dominate the Blind 75 and elevate your problem-solving skills to new heights. Start implementing Trie, unlock its full potential, and embark on your journey to coding excellence.