Datadog coding interview
questions, leaked.
20 problems reported across recent Datadog interviews. Top patterns: array, string, hash table. The list below is what most reported candidates actually saw, plus the honest play if you can't grind all of it.
Datadog's assessment leans heavily on arrays and strings, with 13 array problems across 20 total questions. You're facing 9 easy, 8 medium, and 3 hard problems, so the difficulty is front-loaded. Most candidates prepare for breadth-first search and dynamic programming, but the real volume is arrays. Hash tables show up in 6 problems, often mixed with strings. If you hit a wall on the live assessment, StealthCoder runs invisibly and surfaces a working solution in seconds, no proctor visibility. Your edge isn't grinding harder; it's being ready for what actually appears.
Top problems at Datadog
| # | Problem | Diff | Frequency | Pass % | Patterns |
|---|---|---|---|---|---|
| 01 | Coin Change | MEDIUM | 100.0 | 46% | Array · Dynamic Programming · Breadth-First Search |
| 02 | Most Common Word | EASY | 91.6 | 45% | Array · Hash Table · String |
| 03 | Maximum Depth of N-ary Tree | EASY | 89.4 | 73% | Tree · Depth-First Search · Breadth-First Search |
| 04 | Valid Word Abbreviation | EASY | 86.9 | 37% | Two Pointers · String |
| 05 | Design Circular Queue | MEDIUM | 86.9 | 53% | Array · Linked List · Design |
| 06 | Meeting Scheduler | MEDIUM | 82.4 | 55% | Array · Two Pointers · Sorting |
| 07 | People Whose List of Favorite Companies Is Not a Subset of Another List | MEDIUM | 68.7 | 59% | Array · Hash Table · String |
| 08 | Maximum Vacation Days | HARD | 68.7 | 46% | Array · Dynamic Programming · Matrix |
| 09 | Sliding Window Median | HARD | 68.7 | 39% | Array · Hash Table · Sliding Window |
| 10 | House Robber | MEDIUM | 65.0 | 52% | Array · Dynamic Programming |
| 11 | Design Add and Search Words Data Structure | MEDIUM | 65.0 | 47% | String · Depth-First Search · Design |
| 12 | Binary Tree Maximum Path Sum | HARD | 65.0 | 41% | Dynamic Programming · Tree · Depth-First Search |
| 13 | House Robber II | MEDIUM | 54.9 | 44% | Array · Dynamic Programming |
| 14 | Check If It Is a Straight Line | EASY | 54.9 | 40% | Array · Math · Geometry |
| 15 | Unique Number of Occurrences | EASY | 46.9 | 78% | Array · Hash Table |
| 16 | Binary Search Tree to Greater Sum Tree | MEDIUM | 46.9 | 88% | Tree · Depth-First Search · Binary Search Tree |
| 17 | Odd String Difference | EASY | 46.9 | 61% | Array · Hash Table · String |
| 18 | Find Words That Can Be Formed by Characters | EASY | 46.9 | 71% | Array · Hash Table · String |
| 19 | Greatest Common Divisor of Strings | EASY | 46.9 | 53% | Math · String |
| 20 | Path Sum | EASY | 46.9 | 53% | Tree · 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 Datadog 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- array13 · 65%
- string7 · 35%
- hash table6 · 30%
- dynamic programming5 · 25%
- depth first search5 · 25%
- tree4 · 20%
- breadth first search3 · 15%
- binary tree3 · 15%
- two pointers2 · 10%
- design2 · 10%
Datadog rewards array fluency above all else. Coin Change and the House Robber variants (I and II) appear frequently and combine arrays with dynamic programming, so those patterns are critical. String problems cluster with hash tables and counting (Most Common Word is the archetype), so expect to manipulate strings, count frequencies, and validate formats fast. Tree traversal via depth-first search and breadth-first search shows up in 8 problems total, but only 3 are hard. Design questions like Design Circular Queue and Design Add and Search Words Data Structure test whether you can code under pressure, not just recall algorithms. If you blank on a dynamic programming recurrence mid-OA, StealthCoder surfaces the solution while you stay invisible to the proctor. The hard problems (Sliding Window Median, Binary Tree Maximum Path Sum, Maximum Vacation Days) require combining multiple techniques, so drill those patterns second.
Companies with similar patterns
If you prepped for Datadog, these companies recycle ~60% of the same topics.
You've seen the list.
Now make sure you pass Datadog.
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.
Datadog interview FAQ
How many array problems should I solve before the Datadog OA?+
All 13 of them are fair game. Array appears in 65 percent of their problems. Start with the easy ones (Unique Number of Occurrences, Check If It Is a Straight Line) to build speed, then move to Coin Change and House Robber variants, which are medium and require dynamic programming thinking.
Is dynamic programming really that common in their interviews?+
Yes. Five problems involve DP: Coin Change, Maximum Vacation Days, House Robber (both versions), and Binary Tree Maximum Path Sum. Most are medium difficulty. If you haven't done Coin Change and House Robber more than once, do them now. They recur.
What should I drill first for Datadog?+
Arrays with hash tables. Most Common Word combines both, plus counting. Then move to Coin Change and House Robber to lock in DP patterns. Tree traversal (both DFS and BFS) comes next. Spend 60 percent of prep time on these three topics.
Are the hard problems actually asked?+
Possibly, but they're only 15 percent of the pool (3 out of 20). Binary Tree Maximum Path Sum, Sliding Window Median, and Maximum Vacation Days are the hard ones. If you see one, it's usually a tie-breaker question. Master the medium problems first.
Should I study design questions separately?+
They appear twice: Design Circular Queue and Design Add and Search Words Data Structure. Both are medium. Design questions test implementation speed and edge-case thinking, not new algorithms. Practice them last, after you're solid on arrays, DP, and trees.