http://acm.hdu.edu.cn/showproblem.php?pid=2547
//水题 #include <iostream> #include <cmath> using namespace std; double func(double x, double y, double m, double n) { return (sqrt(x*x + y*y + m*m + n*n - 2*m*x - 2*n*y)); } int main() { int t; double a, b, c, d; cin >> t; while (t--) { cin >> a >> b >> c >> d; printf("%.1lf\n", func((a+c)/2,(b+d)/2, a, b)+func((a+c)/2,(b+d)/2, c, d) ); } return 0; }