foo.cc: In function 'int ws(int)':
foo.cc:10:9: warning: 'x' may be used uninitialized in this function [-Wmaybe-uninitialized]
  return x;
         ^
foo.cc: In function 'void output(int (*)[100], int)':
foo.cc:18:24: warning: 'x' may be used uninitialized in this function [-Wmaybe-uninitialized]
    cout<<setw(ws(n*n)+1)<<a[i][j]<<" ";
                        ^

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