[算法导论]BFS @ Python

class Graph:
def __init__(self):
self.V = []

class Vertex:
def __init__(self, x):
self.key = x
self.color = 'white'
self.d = 10000
self.pi = None
self.adj = []

class Solution:
def BFS(self, G, s):
for u in G.V:
if u != s:
u.color = 'white'
u.d = 10000
u.pi = None
s.color = 'gray'
s.d = 0
s.pi = None
Q = []
Q.append(s)
while Q != []:
u = Q.pop(0)
for v in u.adj:
if v.color == 'white':
v.color = 'gray'
v.d = u.d + 1
v.pi = u
Q.append(v)
u.color = 'black'

if __name__ == '__main__':
G = Graph()
r = Vertex('r')
s = Vertex('s')
t = Vertex('t')
u = Vertex('u')
v = Vertex('v')
w = Vertex('w')
x = Vertex('x')
y = Vertex('y')
r.adj = [s, v]
s.adj = [r, w]
t.adj = [u, w, x]
u.adj = [t, x, y]
v.adj = [r]
w.adj = [s, t, x]
x.adj = [t, u, w, y]
y.adj = [u, x]
G.V = [r, s, t, u, v, w, x, y]
m = Solution()
m.BFS(G, s)
for v in G.V:
if v != s:
print v.key, v.color, v.d, v.pi.key