Transform string to adjacency list
Last updated: November 14, 2025
Quick Overview
Given a string representation of a graph where each node is connected by commas, transform this string into an adjacency list. The output should be a dictionary where each key is a node and its value is a list of connected nodes. For example, the input "A,B,C;B,A;C,B" should produce an adjacency list like {"A": ["B", "C"], "B": ["A", "C"], "C": ["B"]}.
Anduril
November 14, 202538
12
3,301 solved
Given a string representation of a graph where each node is connected by commas, transform this string into an adjacency list. The output should be a dictionary where each key is a node and its value is a list of connected nodes. For example, the input "A,B,C;B,A;C,B" should produce an adjacency list like {"A": ["B", "C"], "B": ["A", "C"], "C": ["B"]}.
This coding problem is frequently asked during Technical Screen at Anduril. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. Anduril 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
- What happens if the input contains duplicates?
- What is the worst-case input for your solution?
- What if the input doesn't fit in memory?
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Practice DSA ProblemsSample Answer
Problem Analysis
The problem requires us to convert a string representation of a graph into an adjacency list format, which is a common way to represent graphs using dictionaries in Python. The graph is represented as...
Approach
- Initialize an empty dictionary: This will hold our adjacency list.
- Split the input string by semicolons to separate each connection.
- Iterate through each connection: For each conn...
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