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115+ IBM questions

IBM interview questions and how to prepare

The questions candidates report from IBM interviews, sorted by how often they come up, with difficulty and topics, plus original practice written in IBM's interview style.

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ZorixOS tracks 115 community-reported IBM interview questions, drawn from an open-source dataset of real interview reports and sorted by how frequently each one comes up. Every question links to its source. Alongside them are 78 original ZorixOS practice questions written in IBM's known interview style (not claimed as asked at IBM), so you can rehearse the real format. Practice any of them out loud in a free AI mock interview tuned to IBM.

Updated July 2026

IBM interview questions candidates report

Community-reported from real IBM interviews (open-source dataset), most-asked first. Showing 60 of 115. Each links to its source.

  1. 3Sum
    ArrayTwo PointersSorting
    Medium100% asked
  2. Count Ways to Group Overlapping Ranges
    ArraySorting
    Medium100% asked
  3. Exclusive Time of Functions
    ArrayStack
    Medium100% asked
  4. Find the Smallest Divisor Given a Threshold
    ArrayBinary Search
    Medium100% asked
  5. Gray Code
    MathBacktrackingBit Manipulation
    Medium100% asked
  6. Rotate Image
    ArrayMathMatrix
    Medium100% asked
  7. Integer to Roman
    Hash TableMathString
    Medium93% asked
  8. Minimum Operations to Make Columns Strictly Increasing
    ArrayGreedyMatrix
    Easy92% asked
  9. Fizz Buzz
    MathStringSimulation
    Easy90% asked
  10. Roman to Integer
    Hash TableMathString
    Easy89% asked
  11. Best Time to Buy and Sell Stock
    ArrayDynamic Programming
    Easy88% asked
  12. Count Vowel Strings in Ranges
    ArrayStringPrefix Sum
    Medium87% asked
  13. Two Sum
    ArrayHash Table
    Easy85% asked
  14. Merge Intervals
    ArraySorting
    Medium84% asked
  15. Meeting Rooms II
    ArrayTwo PointersGreedySorting
    Medium83% asked
  16. Minimum Absolute Difference
    ArraySorting
    Easy82% asked
  17. Minimum Operations to Make All Array Elements Equal
    ArrayBinary SearchSortingPrefix Sum
    Medium82% asked
  18. Number of Divisible Triplet Sums
    ArrayHash Table
    Medium81% asked
  19. Find Pivot Index
    ArrayPrefix Sum
    Easy81% asked
  20. Minimum Operations to Make Median of Array Equal to K
    ArrayGreedySorting
    Medium76% asked
  21. Activity Participants
    Database
    Medium74% asked
  22. Find The First Player to win K Games in a Row
    ArraySimulation
    Medium74% asked
  23. Maximum Profitable Triplets With Increasing Prices I
    ArrayBinary Indexed TreeSegment Tree
    Medium74% asked
  24. The kth Factor of n
    MathNumber Theory
    Medium74% asked
  25. Count the Number of Incremovable Subarrays II
    ArrayTwo PointersBinary Search
    Hard73% asked
  26. Average Value of Even Numbers That Are Divisible by Three
    ArrayMath
    Easy72% asked
  27. Find Occurrences of an Element in an Array
    ArrayHash Table
    Medium72% asked
  28. Find Products of Elements of Big Array
    ArrayBinary SearchBit Manipulation
    Hard72% asked
  29. Find the Array Concatenation Value
    ArrayTwo PointersSimulation
    Easy72% asked
  30. Longest Substring Without Repeating Characters
    Hash TableStringSliding Window
    Medium72% asked
  31. Maximum Profitable Triplets With Increasing Prices II
    ArrayBinary Indexed TreeSegment Tree
    Hard72% asked
  32. Minimum Length of String After Operations
    Hash TableStringCounting
    Medium72% asked
  33. Minimum Levels to Gain More Points
    ArrayPrefix Sum
    Medium72% asked
  34. Sort the Students by Their Kth Score
    ArraySortingMatrix
    Medium72% asked
  35. String Compression
    Two PointersString
    Medium72% asked
  36. Taking Maximum Energy From the Mystic Dungeon
    ArrayPrefix Sum
    Medium72% asked
  37. Type of Triangle
    ArrayMathSorting
    Easy72% asked
  38. Height Checker
    ArraySortingCounting Sort
    Easy71% asked
  39. Largest Number After Digit Swaps by Parity
    SortingHeap (Priority Queue)
    Easy71% asked
  40. Longest Consecutive Sequence
    ArrayHash TableUnion Find
    Medium71% asked
  41. Maximum Units on a Truck
    ArrayGreedySorting
    Easy71% asked
  42. Longest Common Prefix
    StringTrie
    Easy69% asked
  43. Get Equal Substrings Within Budget
    StringBinary SearchSliding WindowPrefix Sum
    Medium68% asked
  44. Valid Parentheses
    StringStack
    Easy68% asked
  45. Count Binary Substrings
    Two PointersString
    Easy67% asked
  46. Letter Combinations of a Phone Number
    Hash TableStringBacktracking
    Medium65% asked
  47. Maximum Sum of Distinct Subarrays With Length K
    ArrayHash TableSliding Window
    Medium65% asked
  48. Minimum Suffix Flips
    StringGreedy
    Medium65% asked
  49. Numbers With Repeated Digits
    MathDynamic Programming
    Hard65% asked
  50. Group Anagrams
    ArrayHash TableStringSorting
    Medium65% asked
  51. Make Lexicographically Smallest Array by Swapping Elements
    ArrayUnion FindSorting
    Medium65% asked
  52. Merge Strings Alternately
    Two PointersString
    Easy65% asked
  53. Lexicographically Smallest String After Substring Operation
    StringGreedy
    Medium62% asked
  54. Merge Sorted Array
    ArrayTwo PointersSorting
    Easy62% asked
  55. Longest Palindromic Substring
    Two PointersStringDynamic Programming
    Medium60% asked
  56. Count Pairs Of Similar Strings
    ArrayHash TableStringBit Manipulation
    Easy58% asked
  57. Number of Divisible Substrings
    Hash TableStringCountingPrefix Sum
    Medium58% asked
  58. Shortest and Lexicographically Smallest Beautiful String
    StringSliding Window
    Medium58% asked
  59. Spiral Matrix
    ArrayMatrixSimulation
    Medium58% asked
  60. Maximum Subarray
    ArrayDivide and ConquerDynamic Programming
    Medium56% asked

These are the 60 most-reported of 115 tracked IBM questions. Create a free account to drill the full set with solutions and an AI interviewer.

Practice questions in IBM's style

Original ZorixOS questions written the way IBM interviews, so you rehearse the real format. Not claimed as asked at IBM.

  1. Imagine a scenario where IBM Cloud Kubernetes Service experiences a sudden surge in user traffic causing latency issues. As a Software Engineer, how would you debug this? Describe the tools and metrics you'd use to identify the bottleneck.

    Software EngineerDebugging and PerformanceTests: Evaluates debugging skills, understanding of distributed systems, and familiarity with cloud infrastructure monitoring.

  2. Design a system for IBM Watson Assistant to handle a 10x increase in concurrent user requests. Consider scalability, fault tolerance, and latency. What architectural choices would you make?

    Software EngineerSystem DesignTests: Assesses system design capabilities, understanding of microservices, load balancing, and caching strategies at scale.

  3. You're given a codebase for an IBM Storage product component that is intermittently failing under high load. Walk me through your process of identifying the root cause. What potential areas would you investigate first?

    Software EngineerDebuggingTests: Tests problem-solving approach, logical deduction, and ability to isolate issues in complex software.

  4. Consider IBM's Red Hat acquisition. If you were designing a new feature for OpenShift's developer console, what are the key technical challenges you anticipate, and how would you approach them?

    Software EngineerTechnical Problem SolvingTests: Gauges understanding of integrating technologies and anticipating technical hurdles in a multi-product environment.

  5. Describe a situation where you had to optimize a piece of code for performance. What was the problem, what approach did you take, and what were the results? Relate this to a potential scenario in an IBM mainframe environment.

    Software EngineerCode OptimizationTests: Evaluates understanding of performance tuning and ability to apply concepts to legacy or high-performance computing environments.

  6. Write a SQL query to find the top 5 IBM Cloud customers by monthly spending on compute resources in the last quarter, considering that `cloud_bills` table has `customer_id`, `resource_type`, `usage_amount`, and `bill_date` and `customer_info` has `customer_id`, `customer_name`.

    Data ScientistSQLTests: Tests SQL proficiency for data retrieval and aggregation.

72+ more IBM-style questions are in the free library, each practiceable live with adaptive follow-ups and an honest scorecard. Start free.

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IBM Interview Questions (2026) | ZorixOS