foo.cc: In function 'int main()':
foo.cc:26:16: warning: unused variable 't' [-Wunused-variable]
         double t= sqrt((x[i]-x[ii])*(x[i]-x[ii])+(y[i]-y[ii])*(y[i]-y[ii]));
                ^

自豪的采用jd5进行评测(github.com/masnn/jd5)