From 1f45095f6030b159f4f08e75934c76e5572356b9 Mon Sep 17 00:00:00 2001
From: Donne Martin <donne.martin@gmail.com>
Date: Sun, 23 Aug 2015 08:08:46 -0400
Subject: [PATCH] Added three state variable visit_state which will be useful
 for more advanced challenges such as topological sort.

---
 graphs_trees/graph/graph.py             | 9 ++++++++-
 graphs_trees/graph/graph_solution.ipynb | 9 ++++++++-
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/graphs_trees/graph/graph.py b/graphs_trees/graph/graph.py
index 5379682..7f8351e 100644
--- a/graphs_trees/graph/graph.py
+++ b/graphs_trees/graph/graph.py
@@ -1,11 +1,18 @@
 from collections import OrderedDict
+from enum import Enum  # Python 2 users: Run pip install enum34
+
+
+class State(Enum):
+    unvisited = 1
+    visited = 2
+    visiting = 3
 
 
 class Node:
 
     def __init__(self, id):
         self.id = id
-        self.visited = False
+        self.visit_state = State.unvisited
         self.adjacent = OrderedDict()  # key = node, val = weight
 
     def __str__(self):
diff --git a/graphs_trees/graph/graph_solution.ipynb b/graphs_trees/graph/graph_solution.ipynb
index 22a2a5a..c0d8bee 100644
--- a/graphs_trees/graph/graph_solution.ipynb
+++ b/graphs_trees/graph/graph_solution.ipynb
@@ -135,13 +135,20 @@
    "source": [
     "%%writefile graph.py\n",
     "from collections import OrderedDict\n",
+    "from enum import Enum  # Python 2 users: Run pip install enum34\n",
+    "\n",
+    "\n",
+    "class State(Enum):\n",
+    "    unvisited = 1\n",
+    "    visited = 2\n",
+    "    visiting = 3\n",
     "\n",
     "\n",
     "class Node:\n",
     "\n",
     "    def __init__(self, id):\n",
     "        self.id = id\n",
-    "        self.visited = False\n",
+    "        self.visit_state = State.unvisited\n",
     "        self.adjacent = OrderedDict()  # key = node, val = weight\n",
     "\n",
     "    def __str__(self):\n",