def kruskal(G) -> "list(namedetuple)":
res = []
u = UnionFind() # initialise union-find DS
for edge in iter(sorted(G.edges, key=lambda x: x.weight)):
# go through all the edges and feed the nodes to the union method
# if their roots are not same
if u.isConnected(edge.node1, edge.node2): continue
u.union(edge.node1, edge.node2)
res.append(edge)
return res
class KruskalMST:
def __init__(self, graph):
self.__G = graph
n = self.__G.V()
self.__uf = UnionFind(self.__G.E() + n)
self.__data = []
self.__mst = []
self.__pq = MiniHeap("weight")
self.createMiniHeap(self.__pq)
self.__mstWeight = 0
while (self.__pq.isEmpty() == False and len(self.__mst) < n):
edge = self.__pq.extractMin()
if (self.__uf.isConnected(edge.v(), edge.w())):
continue
else:
#print "insert ,minedge===",edge.v(),edge.w(),edge.weight()
self.__mst.append(edge)
self.__uf.unionElements(edge.v(), edge.w())
for i in range(len(self.__mst)):
self.__mstWeight += self.__mst[i].weight()
def createMiniHeap(self, pq):
n = self.__G.V()
for i in range(n):
adj = self.__G.adjIterator(self.__G, i)
edge = adj.begin()
while adj.end() == False:
if edge.v() < edge.w():
pq.insert(edge)
edge = adj.next()
def mstEdges(self):
return self.__mst
def result(self):
return self.__mstWeight
