排序组合方法，选出3个数，组成不同的三位数，要求每个三位数不相等

import random
import string
#方法1
def strnum(a,k):
num1,num2=1,1
b=[]
for i in range(1,len(a)+1):
num1=num1*i
for i in range(1,len(a)-k+1):
num2=num2*i
#print num1,num2
while True:
c=string.join(random.sample(a,k)).replace(" ","")
if int(c) not in b:
b.append(int(c))
if len(b)>=(num1/num2):
break
print b
print len(b)

x=['1','2','3','4']
strnum(x,3)

import string
import random
#方法2
b=[]
while True:
a=['1','2','3','4']
s=string.join(random.sample(a,3)).replace(" ","")
if s not in b:
b.append(s)
if len(b)>=24:
break
print b

#方法3
c=[]
for line0 in x:
for line1 in x:
for line2 in x:
if line2!=line0 and line2!=line1 and line0!=line1:
c.append(int(line0+line1+line2))
print c