Trexquant Interview Questions & Experiences

Trexquant·Software Engineer·Technical Phone Screen

Jun 2026

Trexquant software engineer interview that went deep into C++ internals, specifically the rules around implicit default constructor generation. Pretty niche stuff, not your typical leetcode grind.

Under what conditions will the compiler implicitly declare a default constructor for a class, and when does that implicitly-declared constructor end up being defined as deleted?
How do user-declared special member functions like copy/move constructors, copy/move assignment operators, and destructors affect whether a default constructor gets generated at all?
What happens to the implicit default constructor when a class has members or base classes with no default constructor, or when members are references or const-qualified?
Can you give concrete examples of a class that gets an implicit default constructor, one that does not get one at all, and one that gets one but it is defined as deleted?

“Two-part question that sounds like one.”

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Trexquant·Software Engineer·Technical Phone Screen

Jun 2026

Got a coding question at Trexquant that was squarely in data structures territory. Classic median-from-stream problem, the kind you either know cold or fumble through.

Design a data structure that supports adding numbers from a stream one at a time and returning the median of all numbers seen so far at any point.

“The two-heap approach is the right answer here and I knew it, but I fumbled the balancing logic under pressure.”

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Trexquant·Software Engineer·Technical Phone Screen

May 2026

Trexquant SWE interview had me implementing a Trie-based dictionary in C++ with wildcard search support. Pretty focused technical round, no fluff.

Design a Trie-based text dictionary in C++ that supports inserting words and searching for patterns where a '.' character can match any single lowercase letter.

“The insert part was fine, standard Trie node with 26 children.”

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Trexquant·Data Scientist·Technical Phone Screen

May 2026

Interviewed for a Data Scientist role at Trexquant and got a coding problem that felt more like a software engineering screen than anything data-related. The problem was algorithmic and the hint they gave basically told you the solution approach, which was a little odd.

Given two strings s and p where p is a subsequence of s, and an array of removable indices, find the maximum number of characters you can remove from s (in the given order) such that p remains a subsequence of the resulting string.

“They gave away the approach in the hint, which was binary search on k.”

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Trexquant·Software Engineer·Technical Phone Screen

May 2026

C++ fundamentals screening at Trexquant for a software engineer role. After a coding question, the interviewer drilled into language mechanics, specifically pointer const-correctness and container choice. Nothing outrageous, but the follow-ups got detailed fast.

What is the difference between `const int*` and `int* const` in C++? What exactly is immutable in each case, and how do you read declarations like `const int* const` in general?
Explain the difference between `std::map` and `std::unordered_map`. Cover the underlying data structures, operation complexities, ordering guarantees, key type requirements, and when you'd pick one over the other.
If you needed keys in sorted order AND fast average-case lookups, how would you approach that? What are the trade-offs of maintaining both a map and an unordered_map versus sorting on demand?
How could an adversary degrade an `unordered_map` to O(n) per operation, and how do you defend against it?

“I knew the surface answer but fumbled when asked to be precise about which assignment fails to compile.”

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Trexquant·Software Engineer·Technical Phone Screen

May 2026

Interviewed for a Software Engineer role at Trexquant and got hit with a streaming median problem. Pretty classic heap question but the pressure of getting the rebalancing logic right on the spot is no joke.

Design a data structure that accepts integers one at a time from a stream and can return the current median at any point, with O(log n) insertion and O(1) median retrieval.

“My first instinct was to just keep a sorted list and binary search insert, which is technically O(log n) to find the position but O(n) to shift elements.”

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Trexquant·Software Engineer·Technical Phone Screen

May 2026

Trexquant SWE interview had at least one technical coding problem focused on streaming data and efficient median tracking. Pretty standard algorithmic round but the implementation details matter a lot here.

Design a data structure in C++ that supports adding integers from a stream and querying the median at any point, with efficient time complexity for both operations.

“Classic two-heap setup, one max-heap for the lower half and one min-heap for the upper half.”

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Trexquant·Software Engineer·Recruiter / HR Screen

May 2026

Recruiter screen at Trexquant, pretty standard stuff on availability and role fit, but they threw in a C++ fundamentals question that I wasn't fully expecting at this stage.

What constructors and special member functions does a C++ class implicitly have by default?

“Caught me slightly off guard on a recruiter call.”

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Trexquant·Software Engineer·Technical Phone Screen

Apr 2026

Trexquant had me implement a Trie with wildcard search support. Pretty focused technical round, one meaty problem with follow-ups on complexity and recursion depth.

Build a Trie data structure that supports adding words and searching for them, where the search pattern can include '.' as a wildcard matching any single character. Walk through the time/space complexity and explain how you'd handle queries with many wildcards without letting the recursion blow up.

“The basic Trie part was fine, I've done that before.”

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Trexquant·Software Engineer·Executive / Final Round

Apr 2026

Final round at Trexquant with the CEO, which turned out to be part culture chat, part live coding session with basically no warning. The vibe shifted pretty fast and you had to stay on your toes the whole time.

Walk me through one of your resume projects in depth. Why was it technically difficult?
Solve this coding problem live on screen share.

“The CEO pushed back hard on my project.”

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