DFS on graph
Last updated: November 11, 2025
Quick Overview
Implement a Depth-First Search (DFS) algorithm to traverse a given graph represented as an adjacency list. Your function should take the graph and a starting node as input, and return a list of nodes in the order they were visited. Ensure that your solution handles both directed and undirected graphs.
Discord
November 11, 202563
13
3,030 solved
Implement a Depth-First Search (DFS) algorithm to traverse a given graph represented as an adjacency list. Your function should take the graph and a starting node as input, and return a list of nodes in the order they were visited. Ensure that your solution handles both directed and undirected graphs.
This coding problem is frequently asked during Take-home Project at Discord. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. Discord expects candidates to write production-quality code, not just solve the puzzle.
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
- Can you solve this in a single pass?
- What is the worst-case input for your solution?
- How would you test this solution thoroughly?
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 requires implementing a Depth-First Search (DFS) on a graph represented as an adjacency list. The DFS algorithm is suitable here because it explores as far as possible along each branch be...
Approach
- Initialize Data Structures: Create a set to keep track of visited nodes and a list to store the traversal order.
- Define the DFS Function: This recursive function will take a node as inp...
Submit Your Answer
