Transform matrix to adjacency list
Last updated: April 11, 2026
Quick Overview
Given a matrix representing a graph where each element indicates the presence of an edge between nodes, transform this matrix into an adjacency list. The output should be a list of lists, where each sublist contains the neighbors of the corresponding node. Ensure that the adjacency list accurately reflects the connections defined by the input matrix.
SentinelOne
April 11, 202614
5
3,040 solved
Given a matrix representing a graph where each element indicates the presence of an edge between nodes, transform this matrix into an adjacency list. The output should be a list of lists, where each sublist contains the neighbors of the corresponding node. Ensure that the adjacency list accurately reflects the connections defined by the input matrix.
SentinelOne uses this problem in the Technical Screen 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
- Can you optimize the space complexity of your solution?
- How would you parallelize this solution?
- How would your solution change if the input was sorted?
- How would you modify your solution to handle streaming input?
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Practice DSA ProblemsSample Answer
Problem Analysis
The problem requires transforming a matrix representation of a graph into an adjacency list format. The matrix is essentially an adjacency matrix where the presence of an edge between node i and nod...
Approach
- Initialize an empty list called
adjacency_listwith the same number of sublists as there are rows in the matrix. - Loop through each row
iof the matrix:- For each row, loop through each c...
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