C++: Maps - Constructing a String with Specific Constraints

Test Input Reasoning:

Through this testcase, I will verify if the given solution is able to handle and return correct output for the lower edgecase when the length of the map is minimum i.e. 1. This is interesting as the edgecases are expected to have different behavior than the other cases, here since the map is of length 1, the map can only be black or white and thus will help me ensure that the basic logic has been implemented properly.