Add missing algorithm include

Wentzell · Wentzell · commit caececc0072d · 2020-12-09T10:01:21.000-05:00
diff --git a/c++/itertools/itertools.hpp b/c++/itertools/itertools.hpp
@@ -20,6 +20,7 @@
 #include <iterator>
 #include <iostream>
 #include <exception>
+#include <algorithm>
 
 namespace itertools {
 
