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 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
