Citadel Securities Interview Questions

What is the difference between concurrent and multicore systems?

How does std::unordered_map work in C++? Provide an example.

Implement a thread pool for sending messages.

Reverse the words in a sentence string in-place.

Design a random number generator that, given a list of probabilities corresponding to a discrete set of outcomes, outputs each outcome with its specified probability.

Implement a shared pointer class in C++ that manages shared ownership of a dynamically allocated object. Ensure proper reference counting and memory management.

Implement a shared_ptr smart pointer in C++ that manages reference counting and ensures proper deletion of the managed object when no references remain.

How is std::map implemented internally?

You have a scale and 18 balls. One of the balls is slightly heavier than the rest, which are identical. What is the minimum number of times you need to use the scale to determine which ball is the heavy ball?

Implement a service to maximize throughput by increasing the number of processes, given a fixed budget constraint.