置换递归C＃

Question

I have this function that call itself to find all the possible combination with the array of int. The problem is that the program calculate the first combination and then, when the recursion continues, the List of combination still contains that value and i don't understand why.

public static void Permutation(List<int> items, int h, List<int> actualCombination)
    {
        if (h == actualCombination.Count)
        {
            results[results.Count] = actualCombination;
        }
        else
        {
            for (int i = 0; i < items.Count; i++)
            {
                actualCombination.Add(items[i]);

                List<int> temp = new List<int>(items);
                temp.Remove(items[i]);

                Permutation(temp, h, actualCombination);

            }
            return;
        }
    }

after that, i call the function in main. In my case the second parameter specify the combination length."Results" is a Dictionary composed by int as key and List as value that is used to save all the combination.

static void Main(string[] args)
    {

        Permutation(new List<int> { 1, 2, 3 }, 3, new List<int>());



        Console.ReadKey();
    }

Answer 1

我通过复制函数添加之前的List解决了该问题。