Update bfs_exercise.md

Author: groverkds

algorithms/9_BreadthFirstSearch/bfs_exercise.md

@@ -1,7 +1,7 @@
 # BFS_Traversal
 BFS Traversal of a graph in python using graph given in dictionary
 
-Implement a program to find whether a path exists for an airline route or not. The routes are described using graph having nodes. The names of the graphs are named alphabet characters for easy understanding. Print the path if it exists; print the denying statement if it doesn't!
+Implement a function to find whether a path exists for a given set of airline routes. The routes are depicted using graphs as a dictionary of sets, where keys represent as source and elements of sets represent destinations. Print the path if it exists.
 
 Example: A, B, C, D, E, F are the nodes of the graph.
 
@@ -23,14 +23,12 @@ the resultant graph will be :-
 
 ![alt text](https://github.com/nikhilailani/data-structures-algorithms-python/blob/master/algorithms/9_BreadthFirstSearch/DFS_BFS_Graph.png)
 
+Example: Source is A, Destination is D.
 
-**Explanation:** Here, selecting A as source node and D as destination node, the values are passed to the function.
+Expected Output:
 
-Your output should look like this:
-
-'''
-Path exists!
+```
 Path : A->B->D
-'''
+```
 
 [Solution](https://github.com/nikhilailani/data-structures-algorithms-python/blob/master/algorithms/9_BreadthFirstSearch/bfs_exercise_solution.py)