Convert a given integer into its Roman numeral representation. You need to understand the mapping between integer values and Roman symbols to perform the conversion accurately.

Calculate the exclusive execution time for each function given a series of log entries marking function calls and returns. The exclusive time is the time spent within a function, not including time spent in its callees.

You're given daily stock prices. Find the maximum profit you can make by buying and selling the stock once. You must buy before you sell.