Maximum spanning tree using Prim's algorithm

Question

How would this algorithm be changed to give a maximum spanning tree?

MST_prim(G,w,r)
for each u that exists in G.V
   u.key= inf 
   u.pi=NIL
r.key=0
Q=G.V
While Q is not empty 
   u= EXTRACT-MIN(Q)
for each v in G.Adj[u]
if v is in Q and w(u,v)<v.key
       v.pi=u
       v.key=w(u,v)

I tried changing it so that it would give me

u = EXTRACT - MAX(Q) and w(u, v) > v.key

but I don't think that's correct.

Answer 1

If you change all costs to negative and then find with prim mst, the answer to your questions will be abs(mst of the graph(where w = -w)). I think this is the easiest way...