DFS on array
Last updated: September 7, 2025
Quick Overview
Implement a Depth-First Search (DFS) algorithm to traverse a given array, where the array may contain nested arrays. Your function should return a flattened version of the array, preserving the order of elements. For example, given the input `[1, [2, 3], 4]`, the output should be `[1, 2, 3, 4]`.
Elastic
September 7, 20253
12
4,550 solved
Implement a Depth-First Search (DFS) algorithm to traverse a given array, where the array may contain nested arrays. Your function should return a flattened version of the array, preserving the order of elements. For example, given the input `[1, [2, 3], 4]`, the output should be `[1, 2, 3, 4]`.
Elastic uses this problem in the Take-home Project to evaluate your algorithmic thinking. They expect you to discuss multiple approaches, analyze trade-offs between them, and implement the optimal solution with clean, readable code.
What the Interviewer Expects
- Recognize the underlying problem pattern (sliding window, two pointers, BFS/DFS, etc.)
- Discuss multiple approaches and trade-offs before coding
- Implement an optimal solution with clean, production-quality code
- Handle all edge cases including boundary conditions and invalid input
- Optimize both time and space complexity with clear justification
- Test your solution systematically with well-chosen examples
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
- What if the input doesn't fit in memory?
- What happens if the input contains duplicates?
- How would your solution change if the input was sorted?
- Can you solve this in a single pass?
Sharpen Your Skills on Codemia
Practice similar problems with our interactive workspace, get AI feedback, and track your progress.
Practice DSA ProblemsSample Answer
Problem Analysis
The problem at hand requires us to flatten an array that may contain nested arrays. This is a classic case where a Depth-First Search (DFS) strategy is applicable. The reason DFS is suitable here is t...
Approach
The approach involves defining a recursive function that takes an array as input. The function will iterate through each element of the array:
- If the element is an integer, append it to the result ...
Submit Your Answer
