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

It is a C-array of vectors

Example with maxnodes = 5. G[5]

0 -> std::vector 
1 -> std::vector 
2 -> std::vector 
3 -> std::vector 
4 -> std::vector 

If each element of g contains 5 elements, it would look like this

G
-
0 -> {0, 1, 2, 3, 4}
1 -> {0, 1, 2, 3, 4}
2 -> {0, 1, 2, 3, 4}
3 -> {0, 1, 2, 3, 4}
4 -> {0, 1, 2, 3, 4}

Meaning, g[u][j], for example with g[2][3] would correspond to the third element in the vector at the second element of g.

g[2][3]

G
-
0 -> {0, 1, 2, 3, 4}
1 -> {0, 1, 2, 3, 4}
2 -> {0, 1, 2, ***3***, 4}
3 -> {0, 1, 2, 3, 4}
4 -> {0, 1, 2, 3, 4}