leetcode-go/poj/2624.4th-point/main.cc

#include <cstdio>

#define Vector Point

using namespace std;

struct Point {
  double x;
  double y;
  Point(double x, double y) : x(x), y(y) {}
  bool operator==(const Point &that) const {
    return this->x == that.x && this->y == that.y;
  }
  Point operator-(const Point &that) const {
    return Point(this->x - that.x, this->y - that.y);
  }
  Point operator+(const Point &that) const {
    return Point(this->x + that.x, this->y + that.y);
  }
};

int main() {
  double x11, y11, x12, y12, x21, y21, x22, y22;
  while (scanf("%lf%lf%lf%lf", &x11, &y11, &x12, &y12) != EOF) {
    scanf("%lf%lf%lf%lf", &x21, &y21, &x22, &y22);
    Point p1(x11, y11), p2(x12, y12), p3(x21, y21), p4(x22, y22), p5(0, 0);
    if (p1 == p3) {
      p5 = p1 + ((p2 - p1) + (p4 - p3));
    } else if (p1 == p4) {
      p5 = p1 + ((p2 - p1) + (p3 - p4));
    } else if (p2 == p3) {
      p5 = p2 + ((p1 - p2) + (p4 - p3));
    } else {
      p5 = p2 + ((p1 - p2) + (p3 - p4));
    }
    printf("%.3lf %.3lf\n", p5.x, p5.y);
  }
  return 0;
}