For a truly random file, your 1/50 compression scheme that will make it smaller than the original will only make it smaller by 5 or 6 bits, maybe more if you are lucky, but it is an exponential, so realistically, you won't be able to save more than a byte or two, and you can't write that decompressor in two bytes.

The only way to win is to reverse the random number generator used to create the contest file, or to exploit some bias if there is one. But if the file is generated properly, most likely with some CSPRNG, good luck going that route.

The contest creator has to use a random file, any attempt to be clever will actually decrease entropy and may result in the contestant winning.

> The only way to win is to reverse the random number generator used to create the contest file

In that case Mike, the contest creator, may declare the result invalid because you haven't satisfied the intent of the challenge.