Problem: Does G have p vertices such that there are at least q edges between them?
To show that this problem is NP-hard, reduce CLIQUE (known to be NP-hard) to DENSE SUBGRAPH.
Namely, provide a polynomial-time transformation of any instance (G, k) of CLIQUE into an instance (G', p, q) of DENSE SUBGRAPH such that G has a clique of size k if and only if G' has p vertices with at least q edges between them.
I am having difficulty with this problem because I do not know where to start with