def kruskal():
A = []
ds = DisjointSets(V) # make set
for e in elist:
u = e.u
v = e.v
if ds.findset(u) != ds.findset(v):
A.append(e)
ds.union(u, v)
return A
def main():
''' Adjacency List representation. G is a list of lists. '''
G = []
V = []
E = set()
T = set()
id = 0
ds = DisjointSets()
file = open('input.txt', 'r')
for line in file:
line = line.strip()
adjacentVertices = []
first = True
for edge in line.split(' '):
if first:
first = False
continue
node, weight = edge.split(',')
adjacentVertices.append((int(node), int(weight)))
E.add((frozenset([id, int(node)]), int(weight)))
G.append(adjacentVertices)
id += 1
file.close()
E = sorted(E, key=lambda x: x[1])
for i in range(len(G)):
v = ds.makeset(i)
V.append(v)
for edge in E:
[a, b] = edge[0]
if len(T) == len(G) - 1:
break
if ds.findset(V[a]) != ds.findset(V[b]):
T.add(edge[0])
ds.union(V[a], V[b])
print("The edges in the minimum spanning tree are:")
for edge in T:
[a, b] = edge
print(a, b)
def kruskal(G):
G=sorted(G)
# print(G)
ds = DisjointSets()
nodes = []
for i in range(len(G)):
node = ds.makeset(i)
nodes.append(node)
wt=0
for w,u,v in G:
if ds.findset(nodes[u]) != ds.findset(nodes[v]):
wt+=w
ds.union(nodes[u],nodes[v])
print(wt)
def mst_kruskal(self):
"""Returns the set of edges in some
minimum spanning tree (MST) of the graph,
computed using Kruskal's algorithm.
"""
A = set()
forest = DisjointSets(len(self._adj))
edges = self.get_edge_list(True)
edges.sort(key=lambda x: x[1])
for e, w in edges:
if forest.find_set(e[0]) != forest.find_set(e[1]):
A.add(e)
# A = A | {e}
forest.union(e[0], e[1])
return A
def init_ds(size):
ds = DisjointSets()
for i in range(size):
ds.make_set(i)
return ds