Longest Word in Dictionary
Longest Word in Dictionary is a Easy Data Structures and Algorithms interview problem you can solve, run and submit on Thita.ai. It belongs to the Design Patterns pattern, in the Tries subpattern.
How to solve Longest Word in Dictionary
Longest Word in Dictionary is a Trie Implementation problem, part of Design Patterns. Implement Trie data structure for prefix-based operations and autocomplete systems.
Work towards the solution in these steps:
- Consider using a data structure that efficiently supports prefix searching and word construction, such as a Trie.
- Build a Trie from the list of words, where each node represents a character, to help check if prefixes exist.
- While traversing the Trie, keep track of nodes that mark the end of valid words to ensure each prefix is valid.
The reference solution runs in O(n) time and O(t) space.
The Longest Word in Dictionary solution and editorial walks through the full approach with reference code.
Problem statement
Given an array of strings words representing an English Dictionary, return the longest word in words that can be built one character at a time by other words in words.
If there is more than one possible answer, return the longest word with the smallest lexicographical order. If there is no answer, return the empty string.
Example 1: Input: words = ["w","wo","wor","worl","world"] Output: "world" Explanation: The word "world" can be built one character at a time by "w", "wo", "wor", and "worl".
Example 2: Input: words = ["a","banana","app","appl","ap","apply","apple"] Output: "apple" Explanation: Both "apply" and "apple" can be built from other words in the dictionary. However, "apple" is lexicographically smaller than "apply".
Constraints: 1 <= words.length <= 1000 1 <= words[i].length <= 30 words[i] consists of lowercase English letters.
Topics and companies
Topics: Hash Table, Trie.
Reported in interviews at Goldman Sachs, Facebook.
How to practise Longest Word in Dictionary on Thita.ai
Starter code is provided in C, C#, C++, dart, elixir, erlang, Go, Java, JavaScript, Kotlin, PHP, Python, python3, racket, Ruby, Rust, Scala, Swift and TypeScript. Your solution runs against 5 test cases for this problem, with the AI coach available for a hint when you are stuck rather than a finished answer. The reference solution runs in O(n) time and O(t) space.
Open Longest Word in Dictionary in the code editor, or read the Longest Word in Dictionary editorial for a worked solution with its approach and complexity analysis.
Where Longest Word in Dictionary sits in the DSA pattern sheet
Problems related to Longest Word in Dictionary
Other problems that use the same Tries and Design Patterns techniques:
- Design Add and Search Words Data Structure — Medium, same subpattern
- Extra Characters in a String — Medium, same subpattern
- Implement Trie (Prefix Tree) — Medium, same subpattern
- Prefix and Suffix Search — Hard, same subpattern
- Replace Words — Medium, same subpattern
- Word Squares — Hard, same subpattern
Longest Word in Dictionary FAQ
What pattern is used to solve Longest Word in Dictionary?
Longest Word in Dictionary is a Trie Implementation problem. It belongs to the Design Patterns pattern, in the Tries subpattern.
What is the time complexity of Longest Word in Dictionary?
The reference solution runs in O(n) time and O(t) space.
Which companies ask Longest Word in Dictionary?
Longest Word in Dictionary has been reported in interviews at Goldman Sachs, Facebook.