Binary Search on graph

Last updated: July 8, 2025

Quick Overview

Given a directed graph represented as an adjacency list, implement a binary search algorithm to determine if there exists a path between two specified nodes. The input will consist of the graph's adjacency list, the starting node, and the target node. The output should be a boolean indicating whether such a path exists.

LinkedIn
Coding & Algorithms
Machine Learning Engineer
LinkedIn
July 8, 2025
Machine Learning Engineer
Take-home Project
Coding & Algorithms
Medium

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5

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Given a directed graph represented as an adjacency list, implement a binary search algorithm to determine if there exists a path between two specified nodes. The input will consist of the graph's adjacency list, the starting node, and the target node. The output should be a boolean indicating whether such a path exists.

This coding problem is frequently asked during Take-home Project at LinkedIn. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. LinkedIn 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
Hash maps and frequency counting
Binary search and divide and conquer
Time and space complexity analysis
Edge cases and input validation
Data structure selection and trade-offs
Tree structures and recursion
How to Approach This
  1. Clarify input constraints and edge cases before writing code.
  2. Walk through your approach verbally and confirm with the interviewer before coding.
  3. Start with a brute force solution, then optimize. Mention time and space complexity.
  4. Test your solution with examples, including edge cases like empty input or duplicates.
  5. Consider common patterns: sliding window, two pointers, hash map, BFS/DFS, dynamic programming.
Possible Follow-up Questions
  • How would your solution change if the input was sorted?
  • What if the input doesn't fit in memory?
  • Can you solve this in a single pass?
  • What happens if the input contains duplicates?
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Sample Answer
Problem Analysis

This problem requires determining if there exists a path between two specified nodes in a directed graph represented as an adjacency list. The nature of the problem suggests using a graph traversal al...

Approach
  1. Graph Representation: Represent the graph using an adjacency list. For example, for a graph with edges A -> B, A -> C, B -> D, it can be represented as: `{'A': ['B', 'C'], 'B': ['D'], 'C': [],...

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