Implement Trie with O(1) space
Last updated: October 21, 2025
Quick Overview
Implement a Trie data structure that supports insert and search operations with O(1) space complexity for each operation. Your implementation should allow for inserting words and checking if a word exists in the Trie, returning a boolean value for the search operation. Ensure that the Trie can handle lowercase alphabetic characters only.
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October 21, 2025109
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Implement a Trie data structure that supports insert and search operations with O(1) space complexity for each operation. Your implementation should allow for inserting words and checking if a word exists in the Trie, returning a boolean value for the search operation. Ensure that the Trie can handle lowercase alphabetic characters only.
This coding problem is frequently asked during Technical Screen at Visa. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. Visa expects candidates to write production-quality code, not just solve the puzzle.
What the Interviewer Expects
- Identify the correct data structure and algorithm for the problem
- Write clean, bug-free code with proper variable naming
- Analyze time and space complexity correctly
- Handle basic edge cases (empty input, single element)
- Communicate your thought process while coding
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 modify your solution to handle streaming input?
- How would you test this solution thoroughly?
- Can you solve this iteratively instead of recursively (or vice versa)?
- What happens if the input contains duplicates?
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Practice DSA ProblemsSample Answer
Problem Analysis
The problem requires the implementation of a Trie (prefix tree) that supports efficient insertion and searching operations with O(1) space complexity for each operation. The Trie is particularly suita...
Approach
- Node Structure: Each node in the Trie will have an array of 26 elements (for each letter in the English alphabet) to represent the children. Additionally, we will maintain a boolean flag to ind...
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