Well, this moose art is a compiled version of sample class doing all the calculations (in fact this class is a contest solution itself). I took .class file, gzipped it and Base64-encoded. So the main code first decodes and decompresses the
String to get byte[] representation of .class file. Then I create inner anonymous class extending ClassLoader to be able to defineClass() - so that jvm is aware of my Class called '$'. Last step is creating an instance and calling the method '$' plus casting the result to desired Map.
some tricks used:
$:
java identifier for byte[] array
__ = '7' >> 8: __ is an identifier for total class length, the initialization expression is simply 0, it is incremented when reading decompressed stream chunks
1<<('0'>>2) means 1 << (48 / 4) = 1<< 12 = 4096 bytes allocated
$0x7F - ordinary Java identifier starting with $, could be "is" as well
$.length>>0b1111 when calling defineClass means 4096 >> 15 = 0 (look at defineClass signature, this is starting offset)
The .class file is a compiled version of this code:
This "hidden" class could have been retrieved by decompiling the byte[] representation (althought I'm not sure if there are any jdk8 compatible decompilers yet).