C++ vector, what does this code mean?

Question

I have this code:

 const int maxnodes = 5000;
 struct Edge 
 {
   int to, rev;
   int f, cap;
 };

 vector g[maxnodes];

This is qui

Answer 1

I believe others have already explained what each line does well. I'm just pointing out that in the second line,

Edge &e = g[u][j];

the code places the Edge at g[u][j] in a reference, presumably, to make the following code easier to both read and write (instead of repeating g[u][j] multiple times).