def KruskalsAlgorithm(g):
"""
(Graph) -> GraphAsLists
Kruskal's algorithm to find a minimum-cost spanning tree
for the given edge-weighted, undirected graph.
"""
n = g.numberOfVertices
result = GraphAsLists(n)
for v in range(n):
result.addVertex(v)
queue = BinaryHeap(g.numberOfEdges)
for e in g.edges:
weight = e.weight
queue.enqueue(Association(weight, e))
partition = PartitionAsForest(n)
while not queue.isEmpty and partition.count > 1:
assoc = queue.dequeueMin()
e = assoc.value
n0 = e.v0.number
n1 = e.v1.number
s = partition.find(n0)
t = partition.find(n1)
if s != t:
partition.join(s, t)
result.addEdge(n0, n1)
return result
def KruskalsAlgorithm(g):
"""
(Graph) -> GraphAsLists
Kruskal's algorithm to find a minimum-cost spanning tree
for the given edge-weighted, undirected graph.
"""
n = g.numberOfVertices
result = GraphAsLists(n)
for v in xrange(n):
result.addVertex(v)
queue = BinaryHeap(g.numberOfEdges)
for e in g.edges:
weight = e.weight
queue.enqueue(Association(weight, e))
partition = PartitionAsForest(n)
while not queue.isEmpty and partition.count > 1:
assoc = queue.dequeueMin()
e = assoc.value
n0 = e.v0.number
n1 = e.v1.number
s = partition.find(n0)
t = partition.find(n1)
if s != t:
partition.join(s, t)
result.addEdge(n0, n1)
return result
def main(*argv):
"Demostration program number 7."
print Demo7.main.__doc__
SetAsArray.main(*argv)
SetAsBitVector.main(*argv)
MultisetAsArray.main(*argv)
MultisetAsLinkedList.main(*argv)
PartitionAsForest.main(*argv)
PartitionAsForestV2.main(*argv)
PartitionAsForestV3.main(*argv)
return 0
def equivalenceClasses(input, output):
"""
(File, File) -> None
Computes equivalence classes using a partition.
First reads an integer from the input stream that
specifies the size of the universal set.
Then reads pairs of integers from the input stream
that denote equivalent items in the universal set.
Prints the partition on end-of-file.
"""
line = input.readline()
p = PartitionAsForest(int(line))
for line in input.readlines():
words = line.split()
i = int(words[0])
j = int(words[1])
s = p.find(i)
t = p.find(j)
if s is not t:
p.join(s, t)
else:
output.write("redundant pair: %d, %d\n" % (i, j))
output.write(str(p) + "\n")
def equivalenceClasses(input, output):
"""
(File, File) -> None
Computes equivalence classes using a partition.
First reads an integer from the input stream that
specifies the size of the universal set.
Then reads pairs of integers from the input stream
that denote equivalent items in the universal set.
Prints the partition on end-of-file.
"""
line = input.readline()
p = PartitionAsForest(int(line))
for line in input.readlines():
words = line.split()
i = int(words[0])
j = int(words[1])
s = p.find(i)
t = p.find(j)
if s is not t:
p.join(s, t)
else:
output.write("redundant pair: %d, %d\n" % (i, j))
output.write(str(p) + "\n")
