add DFS.py

searching_algo/DFS.py

@@ -0,0 +1,37 @@
+from collections import defaultdict 
+  
+class Graph: 
+  
+    def __init__(self): 
+  
+        self.graph = defaultdict(list) 
+  
+    def addEdge(self,u,v): 
+        self.graph[u].append(v) 
+  
+    def DFSUtil(self,v,visited): 
+  
+        visited[v]= True
+        print v, 
+  
+        for i in self.graph[v]: 
+            if visited[i] == False: 
+                self.DFSUtil(i, visited) 
+  
+  
+    def DFS(self,v): 
+  
+        visited = [False]*(len(self.graph)) 
+  
+        self.DFSUtil(v,visited) 
+  
+  
+g = Graph()
+edges = input("input the number of edges : ")
+print "enter nodes with zero based indexing : "
+for i in range(edges): 
+    a, b = map(int, raw_input().split())
+    g.addEdge(a, b) 
+  
+check = input("DFS check from node : ")
+g.DFS(check)