How to set compiling flags in cpp files (C++)

Thank you for reading my question, I searched everywhere on the net and i couldn't find an answer. I have a test (Olympiad in informatic) next week, The programming language that i'll be using is c++,My code gets compiled by a server which then respond weather my answer was true or false (Wrong compilation is considered as false of course), The problem is that i don't have an access to the compilation phase so i can not set c++ to be compiled as c++11 (Can't set compilation flags). My question is: Is there is any way i can add flags inside my cpp file (which will be uploaded to the server) to enable the c++11? Can it be done with predecessor with #somthing ? Note: I have no access except to the cpp file, NO makefile,nor anything else. Thank you For your help, i really apreciate it.