some more solves

contests/1contest/6t.cpp

@@ -0,0 +1,66 @@
+#include <iostream>
+#include <iomanip>
+#include <cmath>
+
+using std::cout, std::cin, std::endl;
+
+class Point
+{
+public:
+    double x;
+    double y;
+    Point(const double a = 0, const double b = 0) : x{ a }, y{ b } {}
+};
+class Line
+{
+public:
+    // m * x + n * y + k = 0;
+    double n;
+    double m;
+    double k;
+    Line(const Point& a, const Point& b) {
+        m = a.y - b.y;
+        n = b.x - a.x;
+        k = a.x * b.y - b.x * a.y;
+    }
+};
+
+Point* crossPoint(const Line& l_1, const Line& l_2) {
+    double det = l_1.m * l_2.n - l_2.m * l_1.n;
+    if (abs(det) < 1e-9) {
+        return nullptr;
+    }
+
+    double x = (l_1.n * l_2.k - l_2.n * l_1.k) / det;
+    double y = (l_2.m * l_1.k - l_1.m * l_2.k) / det;
+
+    return new Point(x, y);
+}
+
+int main() {
+    double x1, x2, y1, y2;
+    std::cin >> x1 >> y1;
+    std::cin >> x2 >> y2;
+    Line l_1(Point(x1, y1), Point(x2, y2));
+
+    std::cin >> x1 >> y1;
+    std::cin >> x2 >> y2;
+    Line l_2(Point(x1, y1), Point(x2, y2));
+
+    Point* pnt = crossPoint(l_1, l_2);
+    if (pnt != nullptr) {
+        std::cout << std::fixed << std::setprecision(5);
+        std::cout << 1 << " " << pnt->x << " " << pnt->y << std::endl;
+        delete pnt;
+        return 0;
+    }
+
+    double det1 = l_1.n * l_2.k - l_2.n * l_1.k;
+    double det2 = l_1.m * l_2.k - l_2.m * l_1.k;
+
+    if (abs(det1) < 1e-9 && abs(det2) < 1e-9) {
+        std::cout << 2 << std::endl;
+        return 0;
+    }
+    std::cout << 0 << std::endl;
+}