Topological ordering

Question 1
A
7
B
9
C
8
D
6
       Data-Structures       Topological ordering       2016 set-01
Question 1 Explanation: 
Different topological orderings of the vertices of the graph are:

It is observed that (a) is the starting vertex & (f) is the final one.
Also observed that c must come after b & e must come after d.
So,

Hence, there are 6 different topological orderings can be derived.
There is 1 question to complete.