Create dfs-algorithm

graph/dfs-algorithm

@@ -0,0 +1,58 @@
+
+# Python program to print DFS traversal from a 
+# given given graph 
+from collections import defaultdict 
+
+# This class represents a directed graph using 
+# adjacency list representation 
+class Graph: 
+
+    # Constructor 
+    def __init__(self): 
+
+        # default dictionary to store graph 
+        self.graph = defaultdict(list) 
+
+    # function to add an edge to graph 
+    def addEdge(self,u,v): 
+        self.graph[u].append(v) 
+
+    # A function used by DFS 
+    def DFSUtil(self,v,visited): 
+
+        # Mark the current node as visited and print it 
+        visited[v]= True
+        print v, 
+
+        # Recur for all the vertices adjacent to this vertex 
+        for i in self.graph[v]: 
+            if visited[i] == False: 
+                self.DFSUtil(i, visited) 
+
+
+    # The function to do DFS traversal. It uses 
+    # recursive DFSUtil() 
+    def DFS(self,v): 
+
+        # Mark all the vertices as not visited 
+        visited = [False]*(len(self.graph)) 
+
+        # Call the recursive helper function to print 
+        # DFS traversal 
+        self.DFSUtil(v,visited) 
+
+
+# Driver code 
+# Create a graph given in the above diagram 
+g = Graph() 
+g.addEdge(0, 1) 
+g.addEdge(0, 2) 
+g.addEdge(1, 2) 
+g.addEdge(2, 0) 
+g.addEdge(2, 3) 
+g.addEdge(3, 3) 
+
+print "Following is DFS from (starting from vertex 2)"
+g.DFS(2) 
+
+# This code is contributed by Neelam Yadav