Please find at least three methods to find the maximum k-core of an undirected graph.

a) Please prove the complexity of each of these algorithms (show your pseudocode). Ex using big O, and so on

b)- Using which of the three methods saves more time? what is the disadvantage?

c)- How do the different searching methods compare with each other other than that?

Please explain thoroughly.

I'm not asking how to do it with any coding languages, make sure you understand the questions before answering.