3 files changed, 62 insertions, 0 deletions

diff --git a/09_geometry/a.out b/09_geometry/a.out
new file mode 100755
index 0000000..6e5df8b
--- /dev/null
+++ b/09_geometry/a.out
diff --git a/09_geometry/line_segment_intersection_2190.cpp b/09_geometry/line_segment_intersection_2190.cpp
new file mode 100644
index 0000000..2f9aced
--- /dev/null
+++ b/09_geometry/line_segment_intersection_2190.cpp
@@ -0,0 +1,41 @@
+#include <algorithm>
+#include <iostream>
+
+bool inran(long long int a, long long int b, long long int m) {
+        return m >= std::min(a, b) && m <= std::max(a, b);
+}
+
+bool inseg(long long int d, long long int dt, long long int du) {
+        return dt >= 0 && dt <= d && du >= 0 && du <= d;
+}
+
+bool f(long long int x1, long long int y1, long long int x2, long long int y2,
+    long long int x3, long long int y3, long long int x4, long long int y4) {
+        long long int xt = x2-x1, yt = y2-y1;
+        long long int xu = x4-x3, yu = y4-y3;
+        long long int d = xt * (-yu) - yt * (-xu);
+        long long int dt = (x3-x1) * (-yu) - (y3-y1) * (-xu);
+        long long int du = (xt) * (y3-y1) - (yt) * (x3-x1);
+
+        if (d == 0) {
+                // Parallel on different lines
+                if (dt != 0 || du != 0) return false;
+
+                // Parallel, same line
+                return xt == 0 ? 
+                    inran(y1,y2,y3) || inran(y1,y2,y4) || inran(y3,y4,y1) :
+                    inran(x1,x2,x3) || inran(x1,x2,x4) || inran(x3,x4,x1);
+        } else {
+                // Not parallel
+                long long int m = d > 0 ? 1 : -1;
+                return inseg(m*d, m*dt, m*du);
+        }
+}
+
+int main() {
+        long long int x1, y1, x2, y2, x3, y3, x4, y4;
+        int n;
+        std::cin >> n;
+        while (std::cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3 >> x4 >> y4)
+                std::cout << (f(x1,y1,x2,y2,x3,y3,x4,y4) ? "YES\n" : "NO\n");
+}
diff --git a/09_geometry/point_location_test_2189.cpp b/09_geometry/point_location_test_2189.cpp
new file mode 100644
index 0000000..998abb8
--- /dev/null
+++ b/09_geometry/point_location_test_2189.cpp
@@ -0,0 +1,21 @@
+#include <iostream>
+
+struct Point {
+        long long x;
+        long long y;
+        Point operator-(const Point& p) const { return Point{x-p.x, y-p.y}; }
+        long long operator*(const Point& v) { return x * v.y - y * v.x; }
+};
+
+int main() {
+        int t;
+        Point a, b, c;
+        std::cin >> t;
+        for (int i = 0; i < t; i++) {
+                std::cin >> a.x >> a.y >> b.x >> b.y >> c.x >> c.y;
+                auto v = (b-a)*(c-a);
+                if (v > 0) std::cout << "LEFT\n";
+                else if (v < 0) std::cout << "RIGHT\n";
+                else std::cout << "TOUCH\n";
+        }
+}