ServiceNow Coding Interview Questions
26 ServiceNow coding interview problems with full optimal solutions — 15 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 ServiceNow interviewer values, and a FAQ section.
Showing 8 problems of 26
- #16mediumfrequently asked
16. Longest Substring Without Repeating Characters
Find the length of the longest substring with all unique characters using a sliding window. ServiceNow asks this to assess hash-map + two-pointer fluency — the same pattern underpins their duplicate-detection logic in event correlation pipelines.
- #17mediumfrequently asked
17. Number of Islands
Count connected components of '1's in a 2-D grid using DFS or BFS. ServiceNow asks this to test graph traversal reasoning — the same connected-component logic powers their CMDB relationship discovery, where service clusters must be identified from a dependency grid.
- #18mediumfrequently asked
18. Course Schedule
Determine if you can finish all courses given prerequisite dependencies — a cycle-detection problem on a directed graph. ServiceNow asks this because workflow dependency graphs in their automation engine must be acyclic; detecting cycles is a core interview signal.
- #19mediumsometimes asked
19. Clone Graph
Deep-copy a connected undirected graph where each node has a value and a list of neighbors. ServiceNow asks this because CMDB cloning — duplicating a service map with all its CI relationships intact — is a real product operation, and the hash-map-keyed-by-original-node pattern is directly applicable.
- #20mediumfrequently asked
20. Implement Trie (Prefix Tree)
Build a trie data structure supporting insert, search, and prefix-search operations. ServiceNow uses this to assess data-structure design skills — trie-based prefix search is the backbone of their universal search autocomplete that spans incidents, assets, and knowledge articles.
- #21mediumfrequently asked
21. Binary Tree Level Order Traversal
Return all node values of a binary tree grouped by level, using BFS. ServiceNow asks this because hierarchical BFS represents approval tiers in their workflow engine — each level is a stage gate — and the level-grouping technique surfaces directly in their reporting dashboards.
- #22mediumfrequently asked
22. LRU Cache
Design a data structure that supports O(1) get and put with least-recently-used eviction. ServiceNow asks this because their platform caches CMDB records and knowledge article lookups at high QPS, making LRU cache design directly applicable to real engineering work.
- #23mediumsometimes asked
23. Word Break
Determine if a string can be segmented into words from a dictionary using dynamic programming. ServiceNow uses this to test DP problem decomposition — the same bottom-up memoization pattern powers their rule-engine tokenization for workflow trigger parsing.