Question

C#实现有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?都是些什么组合

Answer 1

List<int> number = new List<int>();

for (int i = 1; i <= 4; i++)
{
number.Clear();
number.Add(1);
number.Add(2);
number.Add(3);
number.Add(4);
number.Remove(i);
int a1 = number[0] * 100 + number[1] * 10 + number[2];
int a2 = number[1] * 100 + number[0] * 10 + number[2];
int a5 = number[1] * 100 + number[2] * 10 + number[0];
int a3 = number[0] * 100 + number[2] * 10 + number[1];
int a4 = number[2] * 100 + number[1] * 10 + number[0];
int a6 = number[2] * 100 + number[0] * 10 + number[1];
Console.Write(" " + a1 + " " + a2 + " " + a3 + " " + a4 + " " + a4 + " " + a5 + " " + a6);