DFS on interval list

Last updated: November 30, 2025

Quick Overview

Given a list of intervals, implement a Depth-First Search (DFS) algorithm to determine if there is a valid path that covers all intervals without any overlaps. The input will be a list of intervals represented as pairs of integers, and the output should be a boolean indicating whether such a path exists.

Coinbase
Coding & Algorithms
Machine Learning Engineer
Coinbase
November 30, 2025
Machine Learning Engineer
Take-home Project
Coding & Algorithms
Medium

3

9

4,247 solved


Given a list of intervals, implement a Depth-First Search (DFS) algorithm to determine if there is a valid path that covers all intervals without any overlaps. The input will be a list of intervals represented as pairs of integers, and the output should be a boolean indicating whether such a path exists.

This coding problem is frequently asked during Take-home Project at Coinbase. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. Coinbase 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
Graph algorithms and traversal
Data structure selection and trade-offs
Common algorithm patterns (sliding window, two pointers, BFS/DFS)
Tree structures and recursion
Time and space complexity analysis
Hash maps and frequency counting
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
  • Can you optimize the space complexity of your solution?
  • How would you parallelize this solution?
  • What happens if the input contains duplicates?
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Sample Answer
Problem Analysis

The problem requires us to determine if there exists a valid path through a list of intervals without any overlaps. This can be understood as a graph traversal problem where each interval can be thoug...

Approach
  1. Construct the Graph: First, we will represent the intervals as nodes. For each interval, we will create edges to other intervals that do not overlap (i.e., the end of one interval is less than ...

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