For those who have taken quantitative trading jobs, what types of competitive programming problems that you've done have been the best practice for your work in trading?

This is a question for those who have taken quantitative trading jobs (or internships). What types of competitive programming problems that you’ve done have been the best practice for your work as a quantitative trader? Presumably not dynamic programming…

Here I am asking about on the job, not the questions that get asked in interviews (which could be possibly anything algorithmic under the sun).