Building Your Own Containers

Design problems at HRT give you a list of operations to support and a query count near 10^5. Any call that walks the whole container will time out on the hidden tests. The visible tests won't catch it. They still pass, so a clean sample run doesn't tell you much about whether your design holds up at full size.

The four problems below come from the online assessment and the phone screens, plus one onsite format where you extend a working C++ trading codebase. Most of the time there goes into reading code you didn't write. That part is slow. One problem here practices the same skill at a smaller scale.

Two of the problems take a list of queries and return the answers. The other two take a list of method calls and record what each one returns. If you worked through Machine Coding, the same approach applies. Name the state first, then decide which operation has to stay cheap, and pick a structure that keeps it cheap.

Hudson River TradingPremium lesson · Coding round

The 4 Hudson River Trading problems are below.

1. 1A Premium questionCoding · Medium · Frequently asked
2. 2A Premium questionCoding · Medium
3. 3A Premium questionCoding · Hard

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