def mst_prim(self, r=0):
"""Returns the set of edges in some
minimum spanning tree (MST) of the graph,
computed using Prim's algorithm.
Keyword arguments:
r - vertex id to designate as the root (default is 0).
"""
parent = [None for x in range(len(self._adj))]
Q = PQ()
Q.add(r, 0)
for u in range(len(self._adj)):
if u != r:
Q.add(u, math.inf)
while not Q.is_empty():
u = Q.extract_min()
for v, w in self._adj[u].__iter__(True):
if Q.contains(v) and w < Q.get_priority(v):
parent[v] = u
Q.change_priority(v, w)
A = set()
for v, u in enumerate(parent):
if u != None:
A.add((u, v))
# A = A | {(u,v)}
return A
def MST_Prim(self, r=0) :
parent = [ None for x in range(self.numVertices())]
Q = PQ()
Q.add(r,0)
for u in range(self.numVertices()) :
if u!=r :
Q.add(u,inf)
while not Q.isEmpty() :
u = Q.extractMin()
for v in self._adj[u] :
if Q.contains(v) and self._w[(u,v)] < Q.getPriorityValue(v) :
parent[v] = u
Q.changePriorityValue(v, self._w[(u,v)])
A = set()
for u, v in enumerate(parent) :
if v!=None:
A.add((u,v))
return A