Add needed optimization to Li-Chao

Author: ekzhang

li_chao.cpp

@@ -27,12 +27,13 @@ void add_line(pll ln, int lo=0, int hi=MAXLC, int node=0) {
 	int mid = (lo + hi) / 2;
 	bool l = f(ln, lo) < f(line[node], lo);
 	bool m = f(ln, mid) < f(line[node], mid);
+	bool h = f(ln, hi) < f(line[node], hi);
 	if (m) swap(line[node], ln);
 	if (lo == hi || ln.second == INF)
 		return;
 	else if (l != m)
 		add_line(ln, lo, mid - 1, 2 * node + 1);
-	else
+	else if (h != m)
 		add_line(ln, mid + 1, hi, 2 * node + 2);
 }
 

li_chao_dynamic.cpp

@@ -23,6 +23,7 @@ struct lc_node {
 		int mid = (lo + hi) / 2;
 		bool bl = f(nm, nb, lo) < f(m, b, lo);
 		bool bm = f(nm, nb, mid) < f(m, b, mid);
+		bool bh = f(nm, nb, hi) < f(m, b, hi);
 		if (bm) {
 			swap(nm, m);
 			swap(nb, b);
@@ -33,7 +34,7 @@ struct lc_node {
 			if (!l) l = new lc_node;
 			l->add_line(nm, nb, lo, mid - 1);
 		}
-		else {
+		else if (bh != bm) {
 			if (!r) r = new lc_node;
 			r->add_line(nm, nb, mid + 1, hi);
 		}