Grammarly coding interview
questions, leaked.
27 problems reported across recent Grammarly interviews. Top patterns: string, array, hash table. The list below is what most reported candidates actually saw, plus the honest play if you can't grind all of it.
Grammarly's assessment is deceptively simple until it isn't. You're looking at 27 problems spread across string, array, and hash-table patterns, with 16 medium-difficulty questions sitting in the middle. The medium problems are the real filter: Merge Intervals, Generate Parentheses, Number of Islands, Word Search. They test whether you can combine basic structures into working solutions under pressure. Most candidates drill the easy problems, nail them, then hit a wall on the medium tier. That's where StealthCoder becomes your safety net. If you blank mid-assessment on a backtracking or DP pattern, it surfaces a working solution in seconds, invisible to the proctor.
Top problems at Grammarly
| # | Problem | Diff | Frequency | Pass % | Patterns |
|---|---|---|---|---|---|
| 01 | Merge Intervals | MEDIUM | 100.0 | 49% | Array · Sorting |
| 02 | Remove All Adjacent Duplicates In String | EASY | 93.2 | 72% | String · Stack |
| 03 | Remove All Adjacent Duplicates in String II | MEDIUM | 88.0 | 60% | String · Stack |
| 04 | Insert Delete GetRandom O(1) | MEDIUM | 84.8 | 55% | Array · Hash Table · Math |
| 05 | Generate Parentheses | MEDIUM | 81.1 | 77% | String · Dynamic Programming · Backtracking |
| 06 | Repeated DNA Sequences | MEDIUM | 78.9 | 51% | Hash Table · String · Bit Manipulation |
| 07 | Vowel Spellchecker | MEDIUM | 78.9 | 52% | Array · Hash Table · String |
| 08 | Search in Rotated Sorted Array | MEDIUM | 78.9 | 43% | Array · Binary Search |
| 09 | Perfect Number | EASY | 76.5 | 45% | Math |
| 10 | Sqrt(x) | EASY | 70.5 | 40% | Math · Binary Search |
| 11 | Climbing Stairs | EASY | 70.5 | 54% | Math · Dynamic Programming · Memoization |
| 12 | Number of Islands | MEDIUM | 66.8 | 62% | Array · Depth-First Search · Breadth-First Search |
| 13 | Word Search | MEDIUM | 66.8 | 45% | Array · String · Backtracking |
| 14 | Backspace String Compare | EASY | 62.2 | 49% | Two Pointers · String · Stack |
| 15 | Word Break II | HARD | 62.2 | 54% | Array · Hash Table · String |
| 16 | Word Break | MEDIUM | 56.3 | 48% | Array · Hash Table · String |
| 17 | Logger Rate Limiter | EASY | 56.3 | 77% | Hash Table · Design · Data Stream |
| 18 | Implement Trie (Prefix Tree) | MEDIUM | 56.3 | 68% | Hash Table · String · Design |
| 19 | Unique Paths | MEDIUM | 48.0 | 66% | Math · Dynamic Programming · Combinatorics |
| 20 | Trapping Rain Water | HARD | 48.0 | 65% | Array · Two Pointers · Dynamic Programming |
| 21 | Sum of Left Leaves | EASY | 48.0 | 62% | Tree · Depth-First Search · Breadth-First Search |
| 22 | Set Mismatch | EASY | 48.0 | 45% | Array · Hash Table · Bit Manipulation |
| 23 | Special Binary String | HARD | 48.0 | 64% | String · Recursion |
| 24 | Decode the Slanted Ciphertext | MEDIUM | 48.0 | 49% | String · Simulation |
| 25 | Evaluate Reverse Polish Notation | MEDIUM | 48.0 | 55% | Array · Math · Stack |
| 26 | Maximum Palindromes After Operations | MEDIUM | 48.0 | 43% | Array · Hash Table · String |
| 27 | Clone Graph | MEDIUM | 48.0 | 62% | Hash Table · Depth-First Search · Breadth-First Search |
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 Grammarly OA. The proctor cannot see it. Screen share cannot detect it. Made by a working FAANG engineer who treats the OA the way companies treat hiring: as a game with rules you should know.
Get StealthCoder- string13 · 48%
- array12 · 44%
- hash table10 · 37%
- math6 · 22%
- dynamic programming6 · 22%
- stack5 · 19%
- depth first search4 · 15%
- sorting3 · 11%
- breadth first search3 · 11%
- design3 · 11%
Strings and arrays dominate Grammarly's question pool, appearing in 13 and 12 problems respectively. Hash-table problems (10) often overlap with string work, especially in Repeated DNA Sequences and Vowel Spellchecker. The stack pattern shows up heavily in duplicate-removal problems (both Easy and Medium variants). Dynamic programming and math appear less frequently but are scattered throughout, so you can't ignore them. The hard problems (Word Break II and others) combine multiple patterns at once. Start with string manipulation and array work first, then anchor hash-table solutions. Backtracking and DFS problems are lower frequency but show up in critical positions (Generate Parentheses, Word Search). StealthCoder is the hedge for whatever pattern you didn't drill enough. If a DP formulation doesn't snap into place, you've got a live answer in the exam.
Companies with similar patterns
If you prepped for Grammarly, these companies recycle ~60% of the same topics.
You've seen the list.
Now make sure you pass Grammarly.
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. Made by a working FAANG engineer who treats the OA the way companies treat hiring: as a game with rules you should know. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Grammarly interview FAQ
Should I study string and array problems first for Grammarly?+
Yes. Strings appear in 13 of 27 problems, arrays in 12. Between them, they cover nearly two-thirds of what you'll see. String manipulation (Remove All Adjacent Duplicates variants) and array problems (Merge Intervals, Number of Islands) are your highest-ROI drills. Hash-table work overlaps both heavily, so don't isolate it.
How many medium problems should I solve before the assessment?+
Grammarly's 16 medium problems are your real test. Solve at least 8 to 10 cold under timed conditions. Focus on Merge Intervals, Generate Parentheses, Number of Islands, and Word Search first. These patterns repeat. The easy problems are warm-ups, not the actual bar.
Is dynamic programming critical for this assessment?+
It appears in 6 problems but often combines with other patterns. Generate Parentheses and Word Break II are the hard ones. Climbing Stairs is easy. Skip DP drilling if you're tight on time, but know memoization basics. If you hit a DP problem live and freeze, StealthCoder generates a working approach instantly.
What's the trick with the duplicate-removal problems?+
Both variants (Easy and Medium) use a stack, but the Medium version (Remove All Adjacent Duplicates in String II) requires counting. Master the Easy version first, then move to the harder neighbor problem. These two alone account for foundational stack knowledge Grammarly tests.
Should I practice backtracking separately for Grammarly?+
Backtracking appears in 3 problems (Generate Parentheses, Word Search, Word Break II). Generate Parentheses is the easiest entry point and is Medium-difficulty. If you're short on time, focus on one solid backtracking pattern and move on. You won't see five backtracking problems in the same assessment.