/in/foo.cc: In function 'int main()':
/in/foo.cc:89:25: error: 'g' was not declared in this scope
             double xx = g * -a[j][n - 1];
                         ^
/in/foo.cc:109:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             for (int j = 1; j < ans.size(); j ++) printf(" %d", ans[j]);
                             ~~^~~~~~~~~~~~