uva 12165 - Triangle Hazard（几何）

题目链接：uva 12165 - Triangle Hazard

梅涅劳斯定理：

当直线交

 三边所在直线

 于点

 时，

#include <cstdio>
#include <cstring>
#include <algorithm>

using namespace std;

struct Point {
	double x, y;
	Point (double x = 0, double y = 0): x(x), y(y) {}
	void read () { scanf("%lf%lf", &x, &y); }
	void write () { printf("%lf %lf", x, y); }
	Point operator + (const Point& u) { return Point(x + u.x, y + u.y); }
	Point operator - (const Point& u) { return Point(x - u.x, y - u.y); }
}P, Q, R;

Point resize(Point u, double k) {
	return Point(u.x * k, u.y * k);
}

int main () {
	int cas;
	double m1, m2, m3, m4, m5, m6;
	scanf("%d", &cas);
	while (cas--) {
		P.read(), Q.read(), R.read();
		scanf("%lf%lf%lf%lf%lf%lf", &m1, &m2, &m3, &m4, &m5, &m6);
		double k = (m1/m2) * (m3/m4) * (m5/m6);
		double a = (m5/m6) * (m1/m2 + 1);
		double b = (m1/m2) * (m3/m4 + 1);
		double c = (m3/m4) * (m5/m6 + 1);

		Point pa = R + resize(R - P, (a + k) / (1 - k));
		Point pb = P + resize(P - Q, (b + k) / (1 - k));
		Point pc = Q + resize(Q - R, (c + k) / (1 - k));
		pa.write(), printf(" ");
		pb.write(), printf(" ");
		pc.write(), printf("\n");
	}
	return 0;
}