Apply the DFS-based algorithm to solve the topological sorting problem for the following digraph. (a) Consider a digraph with two 11. (b) What is the time efficiency of the DFS-based algorithm for topological sorting? (c) Can one use the order in which vertices are pushed onto the DFS stack (instead of the order they are popped off it) to solve the topological sorting problem? How can one modify the DFS-based algorithm to avoid reversing the vertex ordering generated by DFS