Create BFS.py

searching_algo/BFS.py

@@ -0,0 +1,42 @@
+from collections import defaultdict 
+  
+#--class for directed graph with adjacency list representation 
+class Graph: 
+	
+    #--Constructor of the class
+    def __init__(self): 
+        #--default dictionary to store graph 
+        self.graph = defaultdict(list) 
+  
+    '''
+    --function to add an edge
+    --inputs, starting point of the graph
+    '''
+    def addEdge(self,u,v): 
+        self.graph[u].append(v) 
+  
+    '''
+    --to print a BFS of graph
+    --inputs, starting point of the graph
+    --Prints the BFS starting from the input point
+    '''
+    def BFS(self, s): 
+  
+        # Mark all the vertices as not visited 
+        visited = [False] * (len(self.graph)) 
+  
+                queue = [] 
+  
+        # Mark the source node as visited and enqueue it 
+        queue.append(s) 
+        visited[s] = True
+  
+        while queue: 
+            s = queue.pop(0) 
+            print (s, end = " ") 
+   
+            for i in self.graph[s]: 
+                if visited[i] == False: 
+                    queue.append(i) 
+                    visited[i] = True
+