IBM coding interview
questions, leaked.
115 problems reported across recent IBM interviews. Top patterns: array, string, hash table. The list below is what most candidates actually saw, plus the honest play if you can't grind all of it.
IBM's assessment leans heavy on arrays. Out of 115 problems, 77 test array manipulation, and they own 28 string problems too. You're looking at 73 medium-difficulty questions, so this isn't a warm-up round. The good news: two-pointers, hash-tables, and sorting appear constantly, which means pattern repetition. The bad news: you'll see every variant of array-slicing, rotation, and range logic they can throw at you. If you blank mid-assessment, StealthCoder sits invisible on your screen and surfaces a working solution in seconds, so you can stay calm and keep moving.
Top problems at IBM
| # | Problem | Diff | Frequency | Pass % | Patterns |
|---|---|---|---|---|---|
| 01 | Find the Smallest Divisor Given a Threshold | MEDIUM | 0.0 | 64% | Array · Binary Search |
| 02 | Exclusive Time of Functions | MEDIUM | 100.0 | 65% | Array · Stack |
| 03 | Integer to Roman | MEDIUM | 92.9 | 69% | Hash Table · Math · String |
| 04 | Fizz Buzz | EASY | 89.9 | 74% | Math · String · Simulation |
| 05 | Roman to Integer | EASY | 88.8 | 65% | Hash Table · Math · String |
| 06 | Best Time to Buy and Sell Stock | EASY | 87.7 | 55% | Array · Dynamic Programming |
| 07 | Count Ways to Group Overlapping Ranges | MEDIUM | 85.3 | 38% | Array · Sorting |
| 08 | Two Sum | EASY | 85.3 | 56% | Array · Hash Table |
| 09 | Meeting Rooms II | MEDIUM | 82.6 | 52% | Array · Two Pointers · Greedy |
| 10 | Rotate Image | MEDIUM | 81.1 | 78% | Array · Math · Matrix |
| 11 | Minimum Absolute Difference | EASY | 81.1 | 71% | Array · Sorting |
| 12 | Minimum Operations to Make All Array Elements Equal | MEDIUM | 81.1 | 37% | Array · Binary Search · Sorting |
| 13 | Number of Divisible Triplet Sums | MEDIUM | 81.1 | 68% | Array · Hash Table |
| 14 | Minimum Operations to Make Median of Array Equal to K | MEDIUM | 75.9 | 47% | Array · Greedy · Sorting |
| 15 | The kth Factor of n | MEDIUM | 73.9 | 70% | Math · Number Theory |
| 16 | Activity Participants | MEDIUM | 73.9 | 72% | Database |
| 17 | Maximum Profitable Triplets With Increasing Prices I | MEDIUM | 73.9 | 55% | Array · Binary Indexed Tree · Segment Tree |
| 18 | Find The First Player to win K Games in a Row | MEDIUM | 73.9 | 39% | Array · Simulation |
| 19 | Count Vowel Strings in Ranges | MEDIUM | 71.7 | 68% | Array · String · Prefix Sum |
| 20 | Merge Intervals | MEDIUM | 71.7 | 49% | Array · Sorting |
| 21 | Longest Substring Without Repeating Characters | MEDIUM | 71.7 | 37% | Hash Table · String · Sliding Window |
| 22 | Count the Number of Incremovable Subarrays II | HARD | 71.7 | 39% | Array · Two Pointers · Binary Search |
| 23 | String Compression | MEDIUM | 71.7 | 58% | Two Pointers · String |
| 24 | Maximum Profitable Triplets With Increasing Prices II | HARD | 71.7 | 43% | Array · Binary Indexed Tree · Segment Tree |
| 25 | Sort the Students by Their Kth Score | MEDIUM | 71.7 | 86% | Array · Sorting · Matrix |
| 26 | Find the Array Concatenation Value | EASY | 71.7 | 71% | Array · Two Pointers · Simulation |
| 27 | Average Value of Even Numbers That Are Divisible by Three | EASY | 71.7 | 62% | Array · Math |
| 28 | Minimum Levels to Gain More Points | MEDIUM | 71.7 | 39% | Array · Prefix Sum |
| 29 | Find Products of Elements of Big Array | HARD | 71.7 | 22% | Array · Binary Search · Bit Manipulation |
| 30 | Type of Triangle | EASY | 71.7 | 45% | Array · Math · Sorting |
| 31 | Find Occurrences of an Element in an Array | MEDIUM | 71.7 | 73% | Array · Hash Table |
| 32 | Minimum Length of String After Operations | MEDIUM | 71.7 | 75% | Hash Table · String · Counting |
| 33 | Taking Maximum Energy From the Mystic Dungeon | MEDIUM | 71.7 | 41% | Array · Prefix Sum |
| 34 | Maximum Units on a Truck | EASY | 69.3 | 74% | Array · Greedy · Sorting |
| 35 | Longest Common Prefix | EASY | 69.3 | 45% | String · Trie |
| 36 | Valid Parentheses | EASY | 66.5 | 42% | String · Stack |
| 37 | Get Equal Substrings Within Budget | MEDIUM | 66.5 | 59% | String · Binary Search · Sliding Window |
| 38 | Count Binary Substrings | EASY | 66.5 | 66% | Two Pointers · String |
| 39 | Letter Combinations of a Phone Number | MEDIUM | 63.5 | 64% | Hash Table · String · Backtracking |
| 40 | Numbers With Repeated Digits | HARD | 63.5 | 43% | Math · Dynamic Programming |
| 41 | Maximum Sum of Distinct Subarrays With Length K | MEDIUM | 63.5 | 43% | Array · Hash Table · Sliding Window |
| 42 | Minimum Suffix Flips | MEDIUM | 63.5 | 73% | String · Greedy |
| 43 | Longest Consecutive Sequence | MEDIUM | 59.9 | 47% | Array · Hash Table · Union Find |
| 44 | Longest Palindromic Substring | MEDIUM | 59.9 | 36% | Two Pointers · String · Dynamic Programming |
| 45 | Merge Sorted Array | EASY | 59.9 | 53% | Array · Two Pointers · Sorting |
| 46 | Lexicographically Smallest String After Substring Operation | MEDIUM | 59.9 | 32% | String · Greedy |
| 47 | Maximum Subarray | MEDIUM | 55.7 | 52% | Array · Divide and Conquer · Dynamic Programming |
| 48 | Shortest and Lexicographically Smallest Beautiful String | MEDIUM | 55.7 | 40% | String · Sliding Window |
| 49 | Spiral Matrix | MEDIUM | 55.7 | 54% | Array · Matrix · Simulation |
| 50 | Number of Divisible Substrings | MEDIUM | 55.7 | 73% | Hash Table · String · Counting |
Frequencies derived from public community-tagged interview reports. Click a row to view on LeetCode.
You have a week, maybe less. You can't out-grind the list above. StealthCoder runs invisibly during the actual IBM OA. The proctor cannot see it. Screen share cannot detect it. Built because the OA filter rejects engineers who'd pass the on-site. That's a broken filter. This is the workaround.
Get StealthCoder- array77 · 67%
- string28 · 24%
- hash table25 · 22%
- sorting24 · 21%
- two pointers23 · 20%
- math16 · 14%
- dynamic programming16 · 14%
- greedy15 · 13%
- prefix sum15 · 13%
- binary search14 · 12%
Start with arrays first. They dominate the problem set, and nearly every medium involves some combination of sorting, binary search, or two-pointer logic. String and hash-table problems cluster tightly around the medium tier, often paired with math questions like Integer to Roman and Roman to Integer. Dynamic programming and greedy appear in 16 and 15 problems respectively, but they're often secondary to array mechanics. Prefix-sum and sliding-window show up in range and grouping problems, so drill those patterns together. Only 9 problems touch hard difficulty, so don't waste time on extreme edge cases. The real lever is nailing the medium array problems fast and clean. When you're live on their assessment, if a sorting-plus-two-pointer hybrid hits you and you're unsure of the merge pattern, StealthCoder handles it while you keep your composure.
Companies with similar patterns
If you prepped for IBM, these companies recycle ~60% of the same topics.
You've seen the list.
Now make sure you pass IBM.
Memorizing every problem above in a week is a fantasy. StealthCoder is the hedge: an AI overlay that's invisible during screen share. It reads the problem on screen and surfaces a working solution in under 2 seconds. Built because the OA filter rejects engineers who'd pass the on-site. That's a broken filter. This is the workaround. Works on HackerRank, CodeSignal, CoderPad, and Karat.
IBM interview FAQ
How many array problems should I solve before the IBM assessment?+
Array problems make up two-thirds of their 115-problem dataset. Aim to solve 20 to 30 core array patterns: rotations, subarrays, ranges, and merges. Focus on medium-difficulty first, since 73 out of 115 problems sit there.
Should I study dynamic programming or greedy first for IBM?+
Neither needs to be first. DP and greedy each appear in 15 to 16 problems, but they're often secondary mechanics layered on top of arrays or sorting. Nail arrays and two-pointers first. DP and greedy will feel natural afterward.
What's the hardest topic I'll face on IBM's assessment?+
Only 9 problems are marked hard, so hard difficulty is not the real bottleneck. The bottleneck is speed and accuracy on medium-difficulty array and string problems. Master those, and you'll run out of time before you hit a truly hard problem.
Do I need to memorize hash-table tricks for IBM?+
Hash-tables appear in 25 problems, many paired with string and math topics like Integer to Roman. You don't need advanced tricks. Know map lookups, frequency counts, and one-pass solutions. Most IBM hash-table problems are straightforward.
How much time should I spend on binary search before the assessment?+
Binary search shows up in 14 problems, often combined with arrays or sorting. It's not a primary focus, but problems like Find the Smallest Divisor make it a useful backup pattern. Spend one to two sessions on it after nailing two-pointers.