Rework graph challenge and solution (#86)

graphs_trees/graph/graph.py

@@ -1,11 +1,10 @@
-from collections import OrderedDict
 from enum import Enum  # Python 2 users: Run pip install enum34
 
 
 class State(Enum):
-    unvisited = 1
+    unvisited = 0
+    visiting = 1
     visited = 2
-    visiting = 3
 
 
 class Node:
@@ -13,25 +12,32 @@ class Node:
     def __init__(self, id):
         self.id = id
         self.visit_state = State.unvisited
-        self.adjacent = OrderedDict()  # key = node, val = weight
+        self.adjacent = {}  # key = node, val = weight
 
     def __str__(self):
         return str(self.id)
 
+    def add_neighbor(self, neighbor, weight=0):
+        self.adjacent[neighbor] = weight
+
 
 class Graph:
 
     def __init__(self):
-        self.nodes = OrderedDict()  # key = node id, val = node
+        self.nodes = {}  # key = node id, val = node
 
     def add_node(self, id):
         node = Node(id)
         self.nodes[id] = node
         return node
 
-    def add_edge(self, source, dest, weight=0):
-        if source not in self.nodes:
-            self.add_node(source)
-        if dest not in self.nodes:
-            self.add_node(dest)
-        self.nodes[source].adjacent[self.nodes[dest]] = weight
+    def add_edge(self, id_source, id_dest, weight=0):
+        if id_source not in self.nodes:
+            self.add_node(id_source)
+        if id_dest not in self.nodes:
+            self.add_node(id_dest)
+        self.nodes[id_source].add_neighbor(self.nodes[id_dest], weight)
+
+    def add_undirected_edge(self, source, dest, weight=0):
+        self.add_edge(source, dest, weight)
+        self.nodes[dest].add_neighbor(self.nodes[source], weight)