Candidates who interviewed at Hudson River Trading in 2025 describe an online assessment of about three coding problems, one or two phone screens of about an hour on coding and C++, and an onsite or superday of three to four rounds. The questions went past LeetCode into internals: balanced BST and k-d tree implementation details, operating systems, networking, floating point, bit manipulation and how a function call works on the machine.
Three 2025 candidates reported offers (two New York software engineers and a US intern). Candidates who were cut mostly struggled with C++ debugging in short slots or with systems topics they had not studied.
Hudson River Trading interview process round by round
| Round | Duration | What candidates reported |
|---|---|---|
| Online assessment | Timed | About three problems; sparse test cases; LeetCode medium level in intern reports |
| Phone screen | About 1 hour | Coding plus floating point, bit manipulation, OS basics; C++ implementation |
| Second phone screen (some) | About 1 hour | C++ fundamentals and how the computer works |
| Onsite / superday | 3-4 rounds, about 75 min each | Data structure internals, OS, networking, coding, system design |
Hudson River Trading interview reports from 2025
These are self-reported write-ups on Taro (jointaro.com) and PracHub. Each is one candidate’s account.
- Software engineer, United States (April 2025, no offer). Reached the final round. Asked to design routing of network packets between one hub and several node servers, plus C++ questions the candidate felt were outdated; their C++20-based answer confused the interviewers. Rated negative.
- Software engineer, New York (July 2025, accepted offer). OA, a one-hour technical phone screen, then the onsite. Topics: floating point, bit manipulation, data structures and algorithms, basic OS concepts, and a basic union-find application.
- Software engineer intern, Atlanta (September 2025, no offer). OA with LeetCode medium problems, then a technical interview implementing a Lines and Squares game in C++. Debugging within the short slot was the hard part.
- Software engineer intern, Canada (September 2025, no offer). OA, two phone screens (general C++, then C++ fundamentals and how computers work), then a superday of three live coding rounds; cut after the second. Asked how a function works under the hood.
- Software engineer, OA only (September 2025, outcome unknown). Three problems: two easy-to-medium, one long data-structure design. The email told candidates to write their own test cases because few were given.
- Software engineer intern, United States (October 2025, accepted offer). Four rounds of about 75 minutes: balanced BSTs, k-d tree internals, operating systems and networking.
- Software engineer, New York (November 2025, offer). Phone screen, a LeetCode medium round, then an onsite with another medium and system design questions. One question was a binary search medium.
Detailed interview experiences
Experience 1: SWE intern, four internals-heavy rounds, offer (October 2025)
Profile: US undergraduate intern candidate who had not yet taken an operating systems course.
Round 1, algorithms: Balanced binary search trees. Questions escalated from basic use and traversal, to rebuilding a tree, to internals such as the cost of walking a subtree compared with random access to nodes.
Round 2, algorithms: k-d tree internals.
Round 3, operating systems: The candidate felt they did poorly without the course, but it went fine overall.
Round 4, networking: Protocols and reliability.
Result: Offer accepted.
Takeaways
- What decided it: Holding up under rapid follow-ups on data structure internals.
- Common fail: Knowing how to use a BST but not how it behaves in memory.
- How to practice: Implement a red-black or AVL tree and a k-d tree once, then explain cache behavior for each operation.
Experience 2: Software engineer, New York, offer (July 2025)
Profile: Full-time software engineer candidate.
Rounds: OA, a one-hour phone screen, then the onsite.
Topics: Floating point, bit manipulation, data structures and algorithms, and basic OS concepts. One question was a basic union-find application. The candidate said the problems were not the hardest but covered a wide range.
Result: Offer accepted.
Takeaways
- What decided it: Breadth: being solid on several systems basics rather than deep on one.
- How to practice: A one-page review sheet on IEEE 754, two’s complement and common bit tricks, plus union-find from memory.
Experience 3: SWE intern, Canada, cut at the superday (September 2025)
Profile: Intern candidate.
Online assessment: The candidate believed it was reviewed rather than auto-scored.
Phone screens: Two. The first on general C++ programming; the second on C++ fundamentals and what happens under the hood.
Superday: Three live coding rounds; eliminated after the second.
Result: No offer, rated positive.
Takeaways
- Common fail: Slow implementation in live coding; the candidate advised expecting heavy implementation-style questions.
- How to practice: Timed C++ implementations of medium problems with no IDE autocomplete, talking through the data structure choice.
Experience 4: SWE intern, Atlanta, C++ game implementation (September 2025)
Profile: Intern candidate.
Rounds: An OA with LeetCode medium problems, then a technical interview implementing a Lines and Squares style game in C++.
Result: No offer, rated neutral.
Takeaway: Write code quickly so there is time to debug; the candidate said debugging inside the slot was the main challenge.
Experience 5: Software engineer, United States, final round (April 2025)
Profile: Experienced C++ engineer.
Final round: System design on routing packets between a hub and multiple node servers, and C++ questions. The candidate answered with C++20 features and found the interviewers expected an older answer, kept prompting until they heard it, and were mostly recent graduates on other teams.
Result: No offer, rated negative.
Takeaway: When a C++ question has an answer that changed across standards, give both: what older code does and what the current standard allows.
Hudson River Trading interview questions that come up often
Coding
- Union-find application
- Binary search (LeetCode medium)
- Lines and Squares game in C++
- A long data-structure design problem in the OA
Data structures and systems
- Balanced BST internals, rebuilding a tree, subtree walk cost
- k-d tree internals
- Floating point and bit manipulation
- How a function works under the hood
- OS concepts; networking protocols and reliability
Design
- Route packets between one hub and several node servers
HRT behavioral questions in these reports
None of these reports describe a long behavioral round; fit questions sit inside recruiter calls and short onsite segments. Sample answers are on the Hudson River Trading behavioral interview questions page. The process, pay and worked technical answers are on the Hudson River Trading interview questions page.
Hudson River Trading interview tips from these reports
Online assessment
- Few test cases are given; write 5 to 10 of your own per problem.
- One problem may be a long data-structure design task, so budget time for it.
Phone screens
- Expect C++ and machine-level questions, not only algorithms.
- Floating point, bit manipulation and OS basics came up in a July 2025 offer.
Onsite
- Rounds of about 75 minutes with rapid follow-ups on internals.
- Study OS and networking even as an intern.
Sources
- Taro: software engineer, United States, April 2025
- Taro: software engineer, New York, July 2025 (offer)
- Taro: software engineer intern, Atlanta, September 2025
- Taro: software engineer intern, Canada, September 2025
- PracHub: HRT software engineer OA, September 2025
- Taro: software engineer intern, United States, October 2025 (offer)
- Taro: software engineer, New York, November 2025
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