def __init__(self, G):
super(Topological, self).__init__()
cyclefinder = DirectedCycle(G)
if not cyclefinder.has_cycle():
dfo = DepthFirstOrder(G)
self.order = dfo.get_reversePost()
else:
self.order = []
def __init__(self, G):
self.orders = []
cyclefinder = DirectedCycle(G)
if not cyclefinder.hasCycle():
dfs = DepthFirstOrder(G)
self.orders = dfs.reversePost()
else:
print("G hasCycle:", end=' ')
print(cyclefinder.cycle())
def __init__(self, G):
self.counts = 0
self.markeds = [False] * G.V()
self.ids = [0] * G.V()
order = DepthFirstOrder(G.reverse())
for s in order.reversePost():
if not self.markeds[s]:
self.dfs(G, s)
self.counts += 1
def __init__(self, G):
self.orders = []
cyclefinder = DirectedCycle(G)
if not cyclefinder.hasCycle():
dfs = DepthFirstOrder(G)
self.orders = dfs.reversePost()
else:
print("G hasCycle:", end=' ')
print(cyclefinder.cycle())
def __init__(self, G):
self.counts = 0
self.markeds = [False]*G.V()
self.ids = [0]*G.V()
order = DepthFirstOrder(G.reverse())
for s in order.reversePost():
if not self.markeds[s]:
self.dfs(G, s)
self.counts += 1
def __init__(self, G):
super(KosarajuSCC, self).__init__()
self.marked = [0 for i in xrange(G.Vcount())]
self.id = [-1 for i in xrange(G.Vcount())]
self.count = 0
order = DepthFirstOrder(G.reverse())
for s in order.get_reversePost()[::-1]: # pop the reverse post stack
if not self.marked[s]:
self.dfs(G, s)
self.count += 1
def __init__(self, G):
finder = DirectedCycle(G)
if finder.has_cycle() is False:
dfo = DepthFirstOrder(G)
self.__order = dfo.reverse_post()
self.__rank = [0] * G.V()
for index, v in enumerate(self.__order):
self.__rank[v] = index
else:
self.__order = None
def __init__(self, G): # count is the number of connected coponents in the digraph self._depth_first_order = DepthFirstOrder(G.reverse()) self._count = 0 self._marked = [False] * G.V() self._id = [0] * G.V() # size of each component self._size = [0] * G.V() for v in self._depth_first_order.reverse_postorder(): if not self._marked[v]: self._dfs(G, v) self._count += 1
def topological_order(sg):
graph = sg.graph()
finder = DirectedCycle(graph)
if finder.has_cycle():
yield 'has_cycle'
return
dfs = DepthFirstOrder(graph)
for v in dfs.reverse_post:
yield (sg.name(v))
class SCC: # contructor takes in a digraph G def __init__(self, G): # count is the number of connected coponents in the digraph self._depth_first_order = DepthFirstOrder(G.reverse()) self._count = 0 self._marked = [False] * G.V() self._id = [0] * G.V() # size of each component self._size = [0] * G.V() for v in self._depth_first_order.reverse_postorder(): if not self._marked[v]: self._dfs(G, v) self._count += 1 # performs DFS for the graph on v def _dfs(self, G, v): self._marked[v] = True self._id[v] = self._count self._size[self._count] = self._size[self._count] + 1 for w in G.adj(v): if not self._marked[w]: self._dfs(G, w) # returns a boolean indicating if v, w are connected def connected(self, v, w): return self._id[v] == self._id[w] # returns the number of connected components def count(self): return self._count # component identifier for v def id(self, v): return self._id[v]
