图的广度优先搜索 （参考算法导论）

#__author__=lx
#__date__=2011-10-03
#__brief__=BFS

from collections import deque

def BFS( G, s ):
d = []
color = []
p = []
L = deque()

for i in range( len( G ) ):
if i != s:
color.append( 'white' )
d.append( 'helloworld' )
p.append( None )
else:
color.append( 'gray' )
d.append( 0 )
p.append( None )

L.append( s )

while ( len( L ) != 0 ):
u = L.popleft()

for v in G[u]:
if cmp( color[v-1],'white' ) == 0:
color[v-1] = 'gray'
d[v-1] = d[u] + 1
p[v-1] = u
L.append(v-1)
color[u] = 'black'
print u + 1

if __name__ == "__main__":
l1 = [ 2, 3 ]
l2 = [ 4, 5, 1 ]
l3 = [ 6, 7, 1 ]
l4 = [ 2, 8 ]
l5 = [ 2, 8 ]
l6 = [ 3, 7 ]
l7 = [ 3, 6 ]
l8 = [ 4, 5 ]

l = [ l1, l2, l3, l4, l5, l6, l7, l8 ]

BFS( l, 1 )