Add code for breadth first algorithm

SearchingAlgorithms/GraphSearch/breadth_first_search.py

@@ -0,0 +1,39 @@
+graph = {'A': set(['B', 'C']),
+         'B': set(['A', 'D', 'E']),
+         'C': set(['A', 'F']),
+         'D': set(['B']),
+         'E': set(['B', 'F']),
+         'F': set(['C', 'E'])
+         }
+
+# here A,B,....,F represents each node and nodes inside set are the one which are connected with main node
+
+
+def bfs_paths(graph, start, goal):
+    """
+    :param graph: complete nodes and vertices are given
+    :param start: Starting point
+    :param goal: Ending point
+    :return: shortest path for the given graph
+    """
+
+    queue = [(start, [start])]
+    while queue:
+        (vertex, path) = queue.pop(0)
+        for next in graph[vertex] - set(path):
+            if next == goal:
+                yield path + [next]
+            else:
+                queue.append((next, path + [next]))
+
+
+def shortest_path(graph, start, goal):
+    try:
+        return next(bfs_paths(graph, start, goal))
+    except StopIteration:
+        return None
+
+if __name__ == '__main__':
+
+    result = shortest_path(graph, 'A', 'F')
+    print "shortest path is: ", ' -> '.join(result)