DFS on array
Last updated: April 16, 2026
Quick Overview
Implement a Depth-First Search (DFS) algorithm to traverse a given array of integers. Your function should take an array as input and return a list of all unique paths from the first element to the last element, where each path consists of indices of the elements visited. Each index can be visited only once in a single path.
Plaid
April 16, 202642
12
3,350 solved
Implement a Depth-First Search (DFS) algorithm to traverse a given array of integers. Your function should take an array as input and return a list of all unique paths from the first element to the last element, where each path consists of indices of the elements visited. Each index can be visited only once in a single path.
Coding interviews at Plaid focus on problem-solving approach as much as the final solution. The interviewer wants to see you break down the problem, consider edge cases, and optimize iteratively. Communication throughout the process is key.
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
- What happens if the input contains duplicates?
- Can you optimize the space complexity of your solution?
- How would your solution change if the input was sorted?
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Practice DSA ProblemsSample Answer
Problem Analysis
To solve this problem, we need to identify that it involves traversing through an array of integers in a way that allows us to explore all unique paths from the first element to the last element, wher...
Approach
- Initialize a list to store all unique paths.
- Define a helper function that takes the current index and a path list as parameters. This function will:
- Append the current index to th...
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