1 files changed, 34 insertions, 0 deletions
diff --git a/content/datastructures/dynamicConvexHull.cpp b/content/datastructures/dynamicConvexHull.cpp
new file mode 100644
index 0000000..2bd67a6
--- /dev/null
+++ b/content/datastructures/dynamicConvexHull.cpp
@@ -0,0 +1,34 @@
+struct Line {
+	mutable ll m, b, p;
+	bool operator<(const Line& o) const {return m < o.m;}
+	bool operator<(ll x) const {return p < x;}
+};
+
+struct HullDynamic : multiset<Line, less<>> {
+	// (for doubles, use inf = 1/.0, div(a,b) = a/b)
+	ll div(ll a, ll b) {return a / b - ((a ^ b) < 0 && a % b);}
+
+	bool isect(iterator x, iterator y) {
+		if (y == end()) {x->p = INF; return false;}
+		if (x->m == y->m) x->p = x->b > y->b ? INF : -INF;
+		else x->p = div(y->b - x->b, x->m - y->m);
+		return x->p >= y->p;
+	}
+
+	void add(ll m, ll b) {
+		auto x = insert({m, b, 0});
+		while (isect(x, next(x))) erase(next(x));
+		if (x != begin()) {
+			--x;
+			while (isect(x, next(x))) erase(next(x));
+		}
+		while (x != begin() && prev(x)->p >= x->p) {
+			--x;
+			isect(x, erase(next(x)));
+	}}
+
+	ll query(ll x) {
+		auto l = *lower_bound(x);
+		return l.m * x + l.b;
+	}
+};