CircleCI Coding Interview Questions
27 CircleCI coding interview problems with full optimal solutions — 16 easy, 8 medium, 3 hard. Every problem ships with multiple approaches (brute-force first, then the optimal), complexity tables for each, company-specific tips on what an CircleCI interviewer values, and a FAQ section.
Showing 8 problems of 27
- #17mediumfoundational
17. Course Schedule
Detect if a directed course prerequisite graph has a cycle, directly mirroring CircleCI's cycle detection in pipeline job dependency graphs.
- #18mediumfoundational
18. Course Schedule II
Return a valid topological ordering of courses, which maps directly to CircleCI's job execution order in a pipeline DAG.
- #19mediumfoundational
19. Number of Islands
Count connected land components in a grid, an abstraction CircleCI uses to reason about isolated sub-graphs within a larger pipeline dependency network.
- #20mediumfoundational
20. Task Scheduler
Compute the minimum time to execute CPU tasks with a cooldown period — directly analogous to CircleCI's job scheduling with resource constraints and cooldown between same-type jobs.
- #21mediumfoundational
21. Clone Graph
Deep-clone a connected undirected graph, testing your ability to handle shared references — an important skill when CircleCI forks pipeline configurations for parallel builds.
- #22mediumfoundational
22. Network Delay Time
Find the time for a signal to reach all nodes using Dijkstra's algorithm, directly modeling how CircleCI measures end-to-end latency across distributed build infrastructure.
- #24mediumfoundational
24. Parallel Courses
Determine the minimum number of semesters to complete all courses in parallel, which maps exactly to CircleCI's minimum pipeline stage count with parallel job execution.
- #25mediumfoundational
25. Find Eventual Safe States
Find all nodes that eventually lead to terminal nodes (no cycles), analogous to identifying pipeline jobs guaranteed to terminate versus those caught in retry loops.