diff --git a/cpp/graph.hpp b/cpp/graph.hpp
index feac06b5febbcda3f9b3e78018181e7022f55e9a..b060f19362e37e55d009fc1f64820d77bc77c868 100644
--- a/cpp/graph.hpp
+++ b/cpp/graph.hpp
@@ -88,7 +88,14 @@ class Graph {
     }
 
     // Assumes valid vertex indices
-    bool hasEdge(const Edge &e) const {
+    bool hasEdge(const Edge& e_) const {
+        Edge e;
+        if (adj[e_.u].size() <= adj[e_.v].size()) {
+            e = e_;
+        } else {
+            e.u = e_.v;
+            e.v = e_.u;
+        }
         for (unsigned int v : adj[e.u]) {
             if (v == e.v)
                 return true;