I understand (partially, as you'll see) the solution provided in analysis section of the problem. During the contest, I understood that traces of the form "AAAA ... AABC for some A, B, C (not necessarily all different)" will bear a solution. But I wasn't sure if greedily selecting the elements will yield the latin square. I tried to read Hall's Marriage Theorem <https://en.wikipedia.org/wiki/Hall%27s_marriage_theorem>, but it went straight over my head.
Could someone explain, in simple terms, what Hall's Marriage Theorem is and when and where I can use it? I'm not looking for proofs at the moment, I'm just trying to understand what the theorem states. -- You received this message because you are subscribed to the Google Groups "Google Code Jam" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/google-code/68641323-c0ce-4754-911c-4c75fa9e1791%40googlegroups.com.
