Graphs

Given:

directed Graph G=(V,E) with the function w: E -> wich every edge gives a mass.
For 2 vertex ui,uj⊆V the longest path of the way from ui to uj should be returned, if there is such a way. The length of a way were given by the sum oft he used edges on the way.

c) if there is one topological order for G. How you can see that there is no path from ui to uj?

d) If there were all topological orders for G. how can you see that there is at least one way from ui to uj