def spanning_tree(nodes, edges, randstream):
"""Given a list of edges, calculate a minimal spanning tree out of them."""
num_nodes = len(nodes)
tree = []
partitions = DisjointSet()
for i in range(num_nodes):
# create a disjoint set where each node is a singleton partition
partitions.add(i)
for edge in edges:
a, b = edge
if partitions.find(a) != partitions.find(b):
# partitions were unconnected: bridge them together
tree.append(edge)
partitions.union(a, b)
if len(tree) == num_nodes - 1:
# minimal spanning tree acquired
break
return tree
def spanning_tree(nodes, edges, randstream): """Given a list of edges, calculate a minimal spanning tree out of them.""" num_nodes = len(nodes) tree = [] partitions = DisjointSet() for i in range(num_nodes): # create a disjoint set where each node is a singleton partition partitions.add(i) for edge in edges: a, b = edge if partitions.find(a) != partitions.find(b): # partitions were unconnected: bridge them together tree.append(edge) partitions.union(a, b) if len(tree) == num_nodes-1: # minimal spanning tree acquired break return tree
def FindNegativeCircle(G):
'''
有向图G
返回一个负圈
'''
V = G.V
E = G.Adjlist
#---------------------------------------------
#采用寻找圈方法
Ds = DisjointSet(V)
for u in E.keys():
curList = E[u]
curNode = curList.head
while curNode!=0:
v = curNode.data
parentU = Ds.find(u)
parentV = Ds.find(v)
if parentU == parentV:
#生成环,找v->u的所有路径的权重
findPath(v,u,V,E,curNode.weight)
else:
#在不同的树中，这条边不会产生环
Ds.union(parentU,parentV)
curNode = curNode.next
from DisjointSet import *
print("Criando o conjunto com subconjuntos disjuntos")
myDS = DisjointSet()
print("Criando uns subconjuntos")
for i in range(5):
myDS.makeset(i)
print("Printando os conjuntos")
myDS.print()
print("Unindo R conjuntos 1 e 2")
myDS.uniaoR(1, 2)
myDS.print()
print("Unindo R conjuntos 1 e 3")
myDS.uniaoR(1, 3)
myDS.print()
print("Unindo R conjuntos 0 e 1")
myDS.uniaoR(0, 1)
myDS.print()
print("Retornando o representante dos elementos")
for i in range(5):
print(str(i) + "-->" + str(myDS.find(i)))
print("Verificando se 1 e 2 fazem parte do mesmo conjunto")
print(myDS.mesmo(1, 2))
print("Verificando se 1 e 4 fazem parte do mesmo conjunto")
print(myDS.mesmo(1, 4))
print("União E de 1 e 4")
myDS.print()
myDS.uniaoE(1, 4)
myDS.print()
