1 files changed, 88 insertions, 0 deletions
diff --git a/test/geometry/segmentIntersection.cpp b/test/geometry/segmentIntersection.cpp
new file mode 100644
index 0000000..9862be5
--- /dev/null
+++ b/test/geometry/segmentIntersection.cpp
@@ -0,0 +1,88 @@
+#include "../util.h"
+constexpr ll EPS = 0;
+#define double ll
+#define polar polar<ll>
+#include <geometry/formulas.cpp>
+#undef polar
+#undef double
+
+// Liegt p auf der Strecke a-b?
+bool pointOnLineSegment(pt a, pt b, pt p) {
+	if (cross(a, b, p) != 0) return false;
+	double dist = norm(a - b);
+	return norm(a - p) <= dist && norm(b - p) <= dist;
+}
+
+// Test auf Streckenschnitt zwischen a-b und c-d.
+bool lineSegmentIntersection(pt a, pt b, pt c, pt d) {
+	if (ccw(a, b, c) == 0 && ccw(a, b, d) == 0)
+			return pointOnLineSegment(a,b,c) ||
+			       pointOnLineSegment(a,b,d) ||
+			       pointOnLineSegment(c,d,a) ||
+			       pointOnLineSegment(c,d,b);
+	return ccw(a, b, c) * ccw(a, b, d) <= 0 &&
+	       ccw(c, d, a) * ccw(c, d, b) <= 0;
+}
+
+#include <geometry/segmentIntersection.cpp>
+
+vector<seg> randomSegs(int n, ll range) {
+	auto ps = Random::points<ll>(n, -range, range);
+	vector<seg> segs(n);
+	for (int i = 0; i < n; i++) {
+		pt b;
+		do {
+			b = Random::point<ll>(-pow(range, 0.8), pow(range, 0.8));
+		} while(norm(b) == 0);
+		segs[i] = {ps[i], ps[i] + b, i};
+	}
+	return segs;
+}
+
+bool naive(vector<seg>& segs) {
+	for (ll i = 0; i < sz(segs); i++) {
+		for (ll j = 0; j < i; j++) {
+			if (lineSegmentIntersection(segs[i].a, segs[i].b, segs[j].a, segs[j].b)) return true;
+		}
+	}
+	return false;
+}
+
+void stress_test(ll range) {
+	ll queries = 0;
+	ll intersection = 0;
+	ll notIntersection = 0;
+	for (int tries = 0; tries < 100'000; tries++) {
+		int n = Random::integer<int>(2, 100);
+		auto segs = randomSegs(n, range);
+		auto [a, b] = intersect(segs);
+		bool got = a >= 0;
+		if (got != (b >= 0)) cerr << "error: invalid ans" << FAIL;
+		auto expected = naive(segs);
+		if (got != expected) cerr << "error: intersection not found" << FAIL;
+		if (got && !lineSegmentIntersection(segs[a].a, segs[a].b, segs[b].a, segs[b].b)) cerr << "error: no intersection" << FAIL;
+		queries += n;
+		intersection += got;
+		notIntersection += !got;
+	}
+	cerr << "tested random queries: " << queries << "(" << intersection << ":" << notIntersection << ")" << endl;
+}
+
+constexpr int N = 1'000'000;
+void performance_test() {
+	timer t;
+	auto segs = randomSegs(N, 1'000'000'000);
+
+	t.start();
+	hash_t hash = intersect(segs).first;
+	t.stop();
+
+	if (t.time > 500) cerr << "too slow: " << t.time << FAIL;
+	cerr << "tested performance: " << t.time << "ms (hash: " << hash << ")" << endl;
+}
+
+int main() {
+	stress_test(100);
+	stress_test(1'000'000'000);
+	performance_test();
+}