@Carl Love 

Thank you so much for this. 

@Carl Love 

Oh, I see, I was confused about why put edges in a set. 

Can you please tell me why is it d := Departures(G,w) instead of d := Departures(G,v) ? 

Also, I tested your code, it worked ! 

Thank you 

@Markiyan Hirnyk 

I think you may see it as 

given a directed graph G and a vertex v in G, computes a spanning tree T for the directed connected component of v in G. This means the following: T is a directed graph, it has the same vertices as the directed connected component of v in G, all directed edges of T are also edges of G, and for every vertex w in T there is exactly one path from v to w in T following directed edges. In particular, T has no circuits. 

http://research.nii.ac.jp/~uno/papers/isaac96web.pdf

@Carl Love 


Thank you very much ! 

could I please ask why ? I know that edges are in pairs, so convert them into a set, but I don't know the rest.