002. 有1、2、3、4四个数，能组成多少个互不相同且无重复的

list_num = [1, 2, 3, 4]

all_num = []

for i in list_num:

for j in list_num:

for k in list_num:

if (i!=j) and (i!=k) and (j!=k):

num = i*100 + j*10 + k

all_num.append(num)

print(all_num)

print('A total of %d numbers.' %len(all_num))