Implement Trie with in-place
Last updated: July 8, 2025
Quick Overview
Implement a Trie data structure that allows for in-place insertion and search of strings. Your implementation should support operations to insert a word, search for a word, and check if any word starts with a given prefix, all while maintaining efficient memory usage. The input will consist of a list of strings for insertion and queries for searching, and the output should indicate the success of each search operation.
Jane Street
July 8, 202521
13
3,281 solved
Implement a Trie data structure that allows for in-place insertion and search of strings. Your implementation should support operations to insert a word, search for a word, and check if any word starts with a given prefix, all while maintaining efficient memory usage. The input will consist of a list of strings for insertion and queries for searching, and the output should indicate the success of each search operation.
This coding problem is frequently asked during Phone Screen at Jane Street. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. Jane Street expects candidates to write production-quality code, not just solve the puzzle.
What the Interviewer Expects
- Quickly identify the optimal approach and its theoretical basis
- Handle complex algorithm design with multiple interacting components
- Write concise, elegant code under time pressure
- Prove correctness of your approach and discuss alternative solutions
- Optimize beyond the obvious: discuss constant factor improvements
- Address follow-up variations and explain how the solution generalizes
Key Topics to Cover
How to Approach This
- Clarify input constraints and edge cases before writing code.
- Walk through your approach verbally and confirm with the interviewer before coding.
- Start with a brute force solution, then optimize. Mention time and space complexity.
- Test your solution with examples, including edge cases like empty input or duplicates.
- Consider common patterns: sliding window, two pointers, hash map, BFS/DFS, dynamic programming.
Possible Follow-up Questions
- How would you parallelize this solution?
- What if the input doesn't fit in memory?
- Can you solve this in a single pass?
- Can you solve this iteratively instead of recursively (or vice versa)?
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Practice DSA ProblemsSample Answer
Problem Analysis
To implement a Trie data structure efficiently, we will utilize a tree structure where each node represents a character in a string. The specific pattern applied here is the Trie structure itself, whi...
Approach
- Node Structure: Create a
TrieNodeclass that contains a dictionarychildrento hold child nodes and a booleanis_end_of_wordto signify the completion of a word. - Trie Class: Crea...
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