包对的C++

#include <iostream>
#include <iomanip>
#include <cmath>
using namespace std;

struct Point {
double x, y;
};

double distance(const Point& p1, const Point& p2) {
return sqrt(pow(p2.x - p1.x, 2) + pow(p2.y - p1.y, 2));
}

int main() {
Point p1, p2, p3;

cin >> p1.x >> p1.y;
cin >> p2.x >> p2.y;
cin >> p3.x >> p3.y;

double a = distance(p1, p2);
double b = distance(p2, p3);
double c = distance(p3, p1);

double perimeter = a + b + c;

cout << fixed << setprecision(2) << perimeter << endl;

return 0;

}