diff --git a/cpp/graph.hpp b/cpp/graph.hpp
index f17e7a43d51d97356827405ba26fbfd48d1ebf2b..feac06b5febbcda3f9b3e78018181e7022f55e9a 100644
--- a/cpp/graph.hpp
+++ b/cpp/graph.hpp
@@ -1,4 +1,5 @@
 #pragma once
+#include <algorithm>
 #include <cassert>
 #include <numeric>
 #include <vector>