class LazyPrimMST:
def __init__(self, ewg):
#ewg is an edge weighted graph
self.pq = MinPQ()
self.marked = [False] * (ewg.v + 1)
self.mst = Queue()
self._visit(ewg, 0)
while not self.pq.isEmpty():
e = self.pq.dequeue()
v = e.either()
w = e.other(v)
if (self.marked[v] == True and self.marked[w] == True):
continue
self.mst.enqueue(e)
if not self.marked[v] == True:
self._visit(ewg, v)
if not self.marked[w] == True:
self._visit(ewg, w)
def _visit(self, ewg, v):
self.marked[v] = True
for e in ewg.adj(v):
if not self.marked[e.other(v)] == True:
self.pq.enqueue(e)
def edges(self):
return self.mst
class LazyPrimMST: def __init__(self,ewg): #ewg is an edge weighted graph self.pq = MinPQ() self.marked = [False] * (ewg.v+1) self.mst = Queue() self._visit(ewg,0) while not self.pq.isEmpty(): e = self.pq.dequeue() v = e.either() w = e.other(v) if (self.marked[v] == True and self.marked[w] == True): continue self.mst.enqueue(e) if not self.marked[v] == True: self._visit(ewg,v) if not self.marked[w] == True : self._visit(ewg,w) def _visit(self,ewg,v): self.marked[v] = True for e in ewg.adj(v): if not self.marked[e.other(v)] == True : self.pq.enqueue(e) def edges(self): return self.mst
class MST:
def __init__(self, G):
self.marked = {}
for vid in G.getVertexIds():
self.marked[vid] = False
self.edges = []
self.pq = MinPQ()
self.weight = 0
self.visit(G, 0)
while not self.pq.isEmpty():
edge = self.pq.delMin()
v = edge.either()
w = edge.other(v)
if self.marked[v] and self.marked[w]:
continue
if not self.marked[v]:
self.visit(G, v)
if not self.marked[w]:
self.visit(G, w)
self.edges.append(edge)
self.weight += edge.getWeight()
def visit(self, G, vid):
self.marked[vid] = True
edges = G.getAdjacentEdges(vid)
for edge in edges:
if not self.marked[edge.other(vid)]:
self.pq.insert(edge)
def getEdges(self):
return self.edges
def getWeight(self):
return self.weight
class LazyPrimMST:
def __init__(self, G):
self.mst = []
self.pq = MinPQ()
self.marked = [False] * G.Vertex()
self.Weight = 0
for v in range(0, G.Vertex()):
if not self.marked[v]:
self.prim(G, v)
#assert(self.check(G))
def prim(self, G, s):
self.scan(G, s)
while not self.pq.isEmpty():
e = self.pq.delMin()
v = e.either()
w = e.other(v)
assert (self.marked[v] or self.marked[w])
if self.marked[v] and self.marked[w]:
continue
self.mst += [e]
self.Weight += e.weight
if not self.marked[v]:
self.scan(G, v)
if not self.marked[w]:
self.scan(G, w)
def scan(self, G, v):
assert (not self.marked[v])
self.marked[v] = True
for e in G.adj[v]:
if not self.marked[e.other(v)]:
self.pq.insert(e)
def edges(self):
return self.mst
def weight(self):
return self.Weight
'''def check(self, G):
class KruskalMST: def __init__(self,ewg): self._mst = Queue() self._pq = MinPQ(ewg.edges()) self._uf = UnionFind(ewg.v+1) while not self._pq.isEmpty() and self._mst.size < ewg.v-1: #get minimum weighted ege on the PQ e = self._pq.dequeue() #get the first vertex v = e.either() #get the second w = e.other(v) if (self._uf.connected(v,w)): continue self._uf.union(v,w) self._mst.enqueue(e) def edges(self): return self._mst
