foo.cc: In function 'void move(int, char, char)':
foo.cc:20:21: warning: 'tmp' may be used uninitialized in this function [-Wmaybe-uninitialized]
   case 'A': As[An++]=tmp;  break;
             ~~~~~~~~^~~~

自豪的采用HydroJudge(https://github.com/hydro-dev/Hydro)进行评测。