From a13f7f90743ccdf72e4e3196e666a23c26b896ec Mon Sep 17 00:00:00 2001
From: Marcin Chrzanowski <marcin.j.chrzanowski@gmail.com>
Date: Wed, 4 Jan 2017 23:08:45 -0500
Subject: Note existence of out edges

---
 src/graph.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/graph.h b/src/graph.h
index b4b300b..7d0ae08 100644
--- a/src/graph.h
+++ b/src/graph.h
@@ -19,6 +19,7 @@ public:
         add_vertex(from);
         add_vertex(to);
         graph_[from].push_back(to);
+        has_out_edges_.insert(from);
     }
 
     const std::set<int> & get_vertices() const {
@@ -28,9 +29,14 @@ public:
     const std::vector<int> & get_neighbors(int vertex) const {
         return graph_.find(vertex)->second;
     }
+
+    bool has_out_edges(int vertex) const {
+        return has_out_edges_.count(vertex) > 0;
+    }
 private:
     std::set<int> vertices_;
     std::map<int, std::vector<int>> graph_;
+    std::set<int> has_out_edges_;
 };
 
 #endif
-- 
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