1 files changed, 18 insertions, 0 deletions
diff --git a/content/geometry/convexHull.cpp b/content/geometry/convexHull.cpp
new file mode 100644
index 0000000..6d89e05
--- /dev/null
+++ b/content/geometry/convexHull.cpp
@@ -0,0 +1,18 @@
+vector<pt> convexHull(vector<pt> pts){
+	sort(all(pts), [](const pt& a, const pt& b){
+		return real(a) == real(b) ? imag(a) < imag(b)
+		                          : real(a) < real(b);
+	});
+	pts.erase(unique(all(pts)), pts.end());
+	int k = 0;
+	vector<pt> h(2 * sz(pts));
+	auto half = [&](auto begin, auto end, int t) {
+		for (auto it = begin; it != end; it++) {
+			while (k > t && cross(h[k-2], h[k-1], *it) <= 0) k--;
+			h[k++] = *it;
+	}};
+	half(all(pts), 1);// Untere Hülle.
+	half(next(pts.rbegin()), pts.rend(), k);// Obere Hülle.
+	h.resize(k);
+	return h;
+}