How to store a graph with a large number of vertices?

Question

C++ / C#

For example, I have a graph with n=1e+5 vertices. I don't have enough memory to store it as a matrix m[n][n]. What should I do then?

Answer 1

For example, vector<vector<pair<int, int>>>where each inner vector<pair<int, int>>contains edges leading from the vertex with the corresponding index, and each pair<int, int>is the destination and weight of the edge.