I think there is an issue on the Empire Enigma puzzle for the test cases 3 and 4 in C++.
If you just print the ints provided as input for those test cases, it seems not to be in line with the description.
I tried to print the length, offset and C values and it gives invalid values (ie length is 1431655646 and shall be a lot less)
The test case 1 and 2 seem to work correctly.
Can anyone confirm this behavior ?