class Graph:
def __init__(self):
self.V = []
class Vertex:
def __init__(self, x):
self.key = x
self.color = 'white'
self.d = 10000
self.f = 10000
self.pi = None
self.adj = []
class Solution:
def Dfs(self, G):
for u in G.V:
u.color = 'white'
u.pi = None
global time
time = 0
for u in G.V:
if u.color == 'white':
list=[u]
self.DfsVisit(G, u, list)
print ''.join([i.key for i in list])
def DfsVisit(self, G, u, list):
global time
time = time + 1
u.d = time
u.color = 'gray'
for v in u.adj:
if v.color == 'white':
list.append(v)
v.pi = u
self.DfsVisit(G, v, list)
u.color = 'black'
time = time + 1
u.f = time
def GraphTransposition(self, G):
for u in G.V:
u.adj = (u.adj,[])
for u in G.V:
for v in u.adj[0]:
v.adj[1].append(u)
for u in G.V:
u.adj = u.adj[1]
return G
def StronglyConnectedComponents(self, G):
self.Dfs(G)
G_Transposition = self.GraphTransposition(G)
G_Transposition.V.sort(key=lambda v: v.f, reverse=True)
self.Dfs(G_Transposition)
if __name__ == '__main__':
a,b,c,d,e,f,g,h = [Vertex(i) for i in ['a','b','c','d','e','f','g','h']]
a.adj = [b]
b.adj = [c,e,f]
c.adj = [d,g]
d.adj = [c,h]
e.adj = [a,f]
f.adj = [g]
g.adj = [f,h]
h.adj = [h]
G = Graph()
G.V = [a,b,c,d,e,f,g,h]
m = Solution()
m.StronglyConnectedComponents(G)
