storing the graph with unknown nodes order

Question

What is the best approach to store the graph with unknown order of nodes in a vector. For example i have node coming in an unknown order like 35,23,89,200,12,89,569 etc... I want to store them in such a way that the memory is not wasted and the nodes are accessed efficiently if in constant time then it will be great. May be some hash function will work but if there is one that can distinguish the nodes please tell me or if there is any other approach for that.

Thanks

Answer 1

Simplest solution I think of is just insert them to your vector in order, and create a map<int,int> to map from their values to their indexes.

In your example:

map[35] == 0
ma[[23] == 1
map[89] == 2
map[200] == 3
map[12] == 4
...

now, access the node i as vector[map[i]]

EDIT:
A second possibility will be to use a set instead of vector to hold elements, but it might not always be desired [set has no duplicates, and will no contain elements in the order you inserted them], but consider if it suits you.