python3--basic2

# 1,2,3,4,5,6,7,8,9 print all the non-duplicated 2 bits numbers consist of these numbers;
# print the counter of the numbers
# L = []
# for i in range(1,10,1):
#     for j in range(1,10,1):
#         if i != j:
#             L.append(10*i+j)
#
# print(L)
# print(len(L))

# if the characters are: 1,2,3,6,8,9 a,b,d,e,f, print all the strings with 2 chars;
# a1 and 1a is looked as repeated string
# save the string into a list
# print the counter of the strings
lst = [1, 2, 3, 6, 8, 9, 'a', 'b', 'd', 'e', 'f']
L = []
for i in range(0, len(lst)-1):
    for j in range(i+1, len(lst)):
        s = str(lst[i]) + str(lst[j])
        L.append(s)
print(L)
print(len(L))