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 11 problems of 26
- #1easyfrequently asked
1. Two Sum
Given an array of integers and a target, return indices of the two numbers that add up to target. ServiceNow asks this to confirm you reach for a hash map for O(n) lookups — the same pattern they use in ticket de-duplication and SLA pair-matching.
- #2easyfrequently asked
2. Valid Parentheses
Given a string of brackets, decide if every opener has a matching closer in the correct order. ServiceNow asks this to confirm you reach for a stack — the same data structure their workflow engine uses to nest sub-flows and rollback approval steps.
- #3easyfrequently asked
3. Merge Two Sorted Lists
Splice two sorted linked lists into one sorted list. ServiceNow asks this to test whether you handle dummy-head + tail-pointer mechanics cleanly — the same shape they use when merging two prioritized ticket queues.
- #6easyfrequently asked
6. Search Insert Position
Find the index where a target should be inserted in a sorted array to keep it sorted. ServiceNow uses this to verify binary-search fluency — the same primitive their SLA timer scheduler uses to insert new deadlines into an ordered heap.
- #12easyfrequently asked
12. Maximum Depth of Binary Tree
Find the maximum depth of a binary tree by counting the longest root-to-leaf path. ServiceNow uses this to probe tree-recursion fundamentals, reflecting their heavy use of hierarchical data models in CMDB and approval-chain trees.
- #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.
- #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.