Points on cycle

#include<cmath>
#include<cstdio>
#include<algorithm>
using namespace std;

const double PI = acos(-1.0);
struct Point
{
     double x, y;

     Point(double x = 0, double y = 0): x(x), y(y){}

     void scan()
     {         scanf("%lf%lf", &x, &y);
     }

    void print()
    {
         printf("%.3lf %.3lf", x, y);
     }

     bool operator < (const Point &other){
         return y < other.y || (y == other.y && x < other.x);
     }
 };

 typedef Point Vector;

 Vector rotate(Vector A, double rad)//向量旋转公式
{
     return Vector(A.x * cos(rad) - A.y * sin(rad), A.y * cos(rad) + A.x * sin(rad));
 }

 int main()
 {
     int t;
     Point p[3];
     scanf("%d", &t);
    while(t--)
    {
        p[0].scan();

        p[1] = rotate(p[0], PI * 2 / 3);//逆时针旋转120度
        p[2] = rotate(p[0], -PI * 2 / 3);//顺时针旋转120度

        if(p[2] < p[1]) swap(p[1], p[2]);

         p[1].print(); putchar(‘  ‘);
         p[2].print(); putchar(‘\n‘);
     }
     return 0;
}