题目：有1、2、3、4个数字，能组成多少个互不相同且无重复数字的三位数？都是多少？

1.程序分析：可填在百位、十位、个位的数字都是1、2、3、4。组成所有的排列后再去-Title: 1, 2, 3, 4 digital, can be composed of a number different from each other and no duplicate numbers three digits? Are how many? Program analysis: can be filled in one hundred and ten digital bits are 1, 2, 3, 4. Composed of all the permutations and then go