【python实战】top1 数字组合——有四个数字：1、2、3、4，能组成多少个互不相同且无重复数字的三位数？各是多少？

count = 0
for a in range(1, 5):
    for b in range(1, 5):
        for c in range(1, 5):
            if (a != b) and (b != c) and (a != c):
                print(100*a+10*b+c)
                count += 1
print(f'一共有{count}种')

import itertools
count = 0
a = [1, 2, 3, 4]
for i in itertools.permutations(a, 3):
    print(i[0]*100+i[1]*10+i[2])
    count += 1
print(f'一共有{count}种')