I got an impression that just specifying the input data took almost 1.5 hours, because of C++ and a decision to have it as a graph, not as a matrix. If an interview is in Python, one would write something like ``grid = [[1,0,0], [1,2,0], [0,2,2]]``, and be done with that part.

Probably you got exhausted after doing all these preparations and debugging issues not related directly to the algorithm. I'm not sure the final solution is correct, it is not tested on a graph with multiple connected segments of the same color. It looks more like a convoluted way to count colors globally, discarding standalone colors, if I understood your solution properly.