Problem database last updated: June 20, 2025
17 problems · 8 Easy, 7 Medium, 2 Hard · Ranked #105 of 458
8 Easy
47% · avg 23%
7 Medium
41% · avg 59%
2 Hard
12% · avg 18%
Based on 17 reported problems, Datadog interviews are in line with industry averages - 12% Hard vs 18% overall.
Compared to the industry average, Datadog puts unusual emphasis on tree (23.5% of problems, 4.2x the industry average), binary-tree (17.6% of problems, 3.6x the industry average), counting (11.8% of problems, 3.5x the industry average). If you're short on time, these are the categories to double down on.
The most common topics are array (64.7%), hash-table (35.3%), string (35.3%), depth-first-search (29.4%). Problems below are sorted by frequency, the ones at the top are asked most often.
| Problem | Difficulty | Frequency | Topics | |
|---|---|---|---|---|
Coin Change You are given an integer array coins representing coins of different denominations and an integer amount representing a total amount of money. | Medium | Very Likely | arraydynamic-programmingbreadth-first-search | Solve |
Most Common Word Given a string paragraph and a string array of the banned words banned, return the most frequent word that is not banned. It is guaranteed there is at least one... | Easy | Very Likely | arrayhash-tablestring | Solve |
Maximum Depth of N-ary Tree Given a n-ary tree, find its maximum depth. | Easy | Very Likely | treedepth-first-searchbreadth-first-search | Solve |
Design Circular Queue Design your implementation of the circular queue. The circular queue is a linear data structure in which the operations are performed based on FIFO (First In Fi... | Medium | Very Likely | arraylinked-listdesign | Solve |
People Whose List of Favorite Companies Is Not a Subset of Another List Given the array favoriteCompanies where favoriteCompanies[i] is the list of favorites companies for the ith person (indexed from 0). | Medium | Likely | arrayhash-tablestring | Solve |
Sliding Window Median The median is the middle value in an ordered integer list. If the size of the list is even, there is no middle value. So the median is the mean of the two middl... | Hard | Likely | arrayhash-tablesliding-window | Solve |
Binary Tree Maximum Path Sum A path in a binary tree is a sequence of nodes where each pair of adjacent nodes in the sequence has an edge connecting them. A node can only appear in the sequ... | Hard | Likely | dynamic-programmingtreedepth-first-search | Solve |
Design Add and Search Words Data Structure Design a data structure that supports adding new words and finding if a string matches any previously added string. | Medium | Likely | stringdepth-first-searchdesign | Solve |
House Robber You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, the only constraint stopping you from rob... | Medium | Likely | arraydynamic-programming | Solve |
House Robber II You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed. All houses at this place are arranged in... | Medium | Likely | arraydynamic-programming | Solve |
Check If It Is a Straight Line You are given an integer array coordinates, coordinates[i] = [x, y], where [x, y] represents the coordinate of a point. Check if these points make a straight li... | Easy | Likely | arraymathgeometry | Solve |
Greatest Common Divisor of Strings For two strings s and t, we say "t divides s" if and only if s = t + t + t + ... + t + t (i.e., t is concatenated with itself one or more times). | Easy | Sometimes | mathstring | Solve |
Odd String Difference You are given an array of equal-length strings words. Assume that the length of each string is n. | Easy | Sometimes | arrayhash-tablestring | Solve |
Unique Number of Occurrences Given an array of integers arr, return true if the number of occurrences of each value in the array is unique or false otherwise. | Easy | Sometimes | arrayhash-table | Solve |
Path Sum Given the root of a binary tree and an integer targetSum, return true if the tree has a root-to-leaf path such that adding up all the values along the path equa... | Easy | Sometimes | treedepth-first-searchbreadth-first-search | Solve |
Find Words That Can Be Formed by Characters You are given an array of strings words and a string chars. | Easy | Sometimes | arrayhash-tablestring | Solve |
Binary Search Tree to Greater Sum Tree Given the root of a Binary Search Tree (BST), convert it to a Greater Tree such that every key of the original BST is changed to the original key plus the sum o... | Medium | Sometimes | treedepth-first-searchbinary-search-tree | Solve |
Coin Change
SolveYou are given an integer array coins representing coins of different denominations and an integer amount representing a total amount of money.
Most Common Word
SolveGiven a string paragraph and a string array of the banned words banned, return the most frequent word that is not banned. It is guaranteed there is at least one...
Maximum Depth of N-ary Tree
SolveGiven a n-ary tree, find its maximum depth.
Design Circular Queue
SolveDesign your implementation of the circular queue. The circular queue is a linear data structure in which the operations are performed based on FIFO (First In Fi...
People Whose List of Favorite Companies Is Not a Subset of Another List
SolveGiven the array favoriteCompanies where favoriteCompanies[i] is the list of favorites companies for the ith person (indexed from 0).
Sliding Window Median
SolveThe median is the middle value in an ordered integer list. If the size of the list is even, there is no middle value. So the median is the mean of the two middl...
Binary Tree Maximum Path Sum
SolveA path in a binary tree is a sequence of nodes where each pair of adjacent nodes in the sequence has an edge connecting them. A node can only appear in the sequ...
Design Add and Search Words Data Structure
SolveDesign a data structure that supports adding new words and finding if a string matches any previously added string.
House Robber
SolveYou are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, the only constraint stopping you from rob...
House Robber II
SolveYou are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed. All houses at this place are arranged in...
Check If It Is a Straight Line
SolveYou are given an integer array coordinates, coordinates[i] = [x, y], where [x, y] represents the coordinate of a point. Check if these points make a straight li...
Greatest Common Divisor of Strings
SolveFor two strings s and t, we say "t divides s" if and only if s = t + t + t + ... + t + t (i.e., t is concatenated with itself one or more times).
Odd String Difference
SolveYou are given an array of equal-length strings words. Assume that the length of each string is n.
Unique Number of Occurrences
SolveGiven an array of integers arr, return true if the number of occurrences of each value in the array is unique or false otherwise.
Path Sum
SolveGiven the root of a binary tree and an integer targetSum, return true if the tree has a root-to-leaf path such that adding up all the values along the path equa...
Find Words That Can Be Formed by Characters
SolveYou are given an array of strings words and a string chars.
Binary Search Tree to Greater Sum Tree
SolveGiven the root of a Binary Search Tree (BST), convert it to a Greater Tree such that every key of the original BST is changed to the original key plus the sum o...
Frequency scores are based on crowdsourced interview reports. A higher score means the problem has been reported more often in recent Datadog interviews.
Very Likely
75-100%
Likely
50-74%
Sometimes
25-49%
Rare
0-24%
Datadog interviews focus heavily on array, hash-table, string problems. If you're short on time, these are the categories to prioritize. The problems on this page are sorted by frequency, so start from the top and work your way down.
Beyond solving problems, practice explaining your approach. Datadog interviewers care about your thought process - how you break down a problem, consider edge cases, and evaluate tradeoffs between solutions. A clean O(n) solution you can explain clearly beats an O(log n) solution you can't articulate.
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Datadog has been reported to ask 17 distinct coding problems. The most common topics are array, hash-table, string. 8 are Easy difficulty, 7 are Medium, and 2 are Hard. Problems are sorted by frequency - the ones at the top are asked most often.
Based on 17 reported problems, Datadog interviews are in line with industry averages - 12% Hard vs 18% overall. 41% of questions are Medium difficulty. Focus on the high-frequency Medium problems first, then work through the Hard ones.
Start with the highest-frequency problems listed on this page. Focus on the core topics: array, hash-table, string. Practice solving them under time pressure and explaining your approach out loud. Mock interviews with AI can simulate the real experience.
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