Do you know the graph contraction algorithm?

Question

Java

Contraction. By shrinking we mean the operation of removing an edge and identifying its end vertices. A graph C is a contractible graph to a graph if H can be obtained from G by a sequence of contractions.
Closure or identification. A pair of vertices v is said to be closed (or identified) in G if they are replaced by a new vertex such that all edges in G that are incident become incident to the new vertex.
Is there an optimal graph contraction algorithm? The graph vertex limit is <= 20 , so the data structure is not important . However, as I understand it, the adjacency matrix is ​​unsuitable here for a simple reason - the number of vertices becomes smaller, and you will have to constantly "play" with memory.

Answer 1

You looked at Karger's minimum cut algorithm , it's based on contraction. What is your task? Want to shrink the graph down to 20 vertices?