Problem database last updated: June 20, 2025
9 problems · 4 Easy, 2 Medium, 3 Hard · Ranked #168 of 458
4 Easy
44% · avg 23%
2 Medium
22% · avg 59%
3 Hard
33% · avg 18%
Based on 9 reported problems, Hudson River Trading interviews are significantly harder than average - 33% Hard vs 18% across all companies.
Compared to the industry average, Hudson River Trading puts unusual emphasis on graph (33.3% of problems, 11.2x the industry average), math (33.3% of problems, 2.6x the industry average), greedy (22.2% of problems, 2.6x the industry average). If you're short on time, these are the categories to double down on.
The most common topics are array (44.4%), graph (33.3%), math (33.3%), string (22.2%). Problems below are sorted by frequency, the ones at the top are asked most often.
| Problem | Difficulty | Frequency | Topics | |
|---|---|---|---|---|
Detect Pattern of Length M Repeated K or More Times Given an array of positive integers arr, find a pattern of length m that is repeated k or more times. | Easy | Very Likely | arrayenumeration | Solve |
Add Edges to Make Degrees of All Nodes Even There is an undirected graph consisting of n nodes numbered from 1 to n. You are given the integer n and a 2D array edges where edges[i] = [ai, bi] indicates th... | Hard | Very Likely | hash-tablegraph | Solve |
Longest Path With Different Adjacent Characters You are given a tree (i.e. a connected, undirected graph that has no cycles) rooted at node 0 consisting of n nodes numbered from 0 to n - 1. The tree is repres... | Hard | Very Likely | arraystringtree | Solve |
Maximum Total Importance of Roads You are given an integer n denoting the number of cities in a country. The cities are numbered from 0 to n - 1. | Medium | Very Likely | greedygraphsorting | Solve |
Convert Integer to the Sum of Two No-Zero Integers No-Zero integer is a positive integer that does not contain any 0 in its decimal representation. | Easy | Very Likely | math | Solve |
Number of Steps to Reduce a Number to Zero Given an integer num, return the number of steps to reduce it to zero. | Easy | Very Likely | mathbit-manipulation | Solve |
Maximum 69 Number You are given a positive integer num consisting only of digits 6 and 9. | Easy | Very Likely | mathgreedy | Solve |
Maximum Score From Grid Operations You are given a 2D matrix grid of size n x n. Initially, all cells of the grid are colored white. In one operation, you can select any cell of indices (i, j), a... | Hard | Very Likely | arraydynamic-programmingmatrix | Solve |
Remove Comments Given a C++ program, remove comments from it. The program source is an array of strings source where source[i] is the ith line of the source code. This represen... | Medium | Likely | arraystring | Solve |
Detect Pattern of Length M Repeated K or More Times
SolveGiven an array of positive integers arr, find a pattern of length m that is repeated k or more times.
Add Edges to Make Degrees of All Nodes Even
SolveThere is an undirected graph consisting of n nodes numbered from 1 to n. You are given the integer n and a 2D array edges where edges[i] = [ai, bi] indicates th...
Longest Path With Different Adjacent Characters
SolveYou are given a tree (i.e. a connected, undirected graph that has no cycles) rooted at node 0 consisting of n nodes numbered from 0 to n - 1. The tree is repres...
Maximum Total Importance of Roads
SolveYou are given an integer n denoting the number of cities in a country. The cities are numbered from 0 to n - 1.
Convert Integer to the Sum of Two No-Zero Integers
SolveNo-Zero integer is a positive integer that does not contain any 0 in its decimal representation.
Number of Steps to Reduce a Number to Zero
SolveGiven an integer num, return the number of steps to reduce it to zero.
Maximum 69 Number
SolveYou are given a positive integer num consisting only of digits 6 and 9.
Maximum Score From Grid Operations
SolveYou are given a 2D matrix grid of size n x n. Initially, all cells of the grid are colored white. In one operation, you can select any cell of indices (i, j), a...
Remove Comments
SolveGiven a C++ program, remove comments from it. The program source is an array of strings source where source[i] is the ith line of the source code. This represen...
Frequency scores are based on crowdsourced interview reports. A higher score means the problem has been reported more often in recent Hudson River Trading interviews.
Very Likely
75-100%
Likely
50-74%
Sometimes
25-49%
Rare
0-24%
Hudson River Trading interviews focus heavily on array, graph, math 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. Hudson River Trading 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.
Looking for more companies? Browse all 458 companies in our directory, or sharpen your fundamentals with our free data structure visualizers and AI-powered DSA tutor.
Hudson River Trading has been reported to ask 9 distinct coding problems. The most common topics are array, graph, math. 4 are Easy difficulty, 2 are Medium, and 3 are Hard. Problems are sorted by frequency - the ones at the top are asked most often.
Based on 9 reported problems, Hudson River Trading interviews are significantly harder than average - 33% Hard vs 18% across all companies. 22% 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, graph, math. Practice solving them under time pressure and explaining your approach out loud. Mock interviews with AI can simulate the real experience.
Simulate a real Hudson River Trading coding interview with an AI interviewer. Get a scorecard with specific feedback on your problem-solving, code quality, and communication.
Simulate a Hudson River Trading interview with AIarrow_forward
