C#递归算法和排列算法

static void  Main(string[] args)
{
    int[] sum = new int[30];
    for (int i = 0; i < sum.Length; i++)
    {
        sum[i] = process1(i);
        Console.WriteLine(sum[i]);
    }
}
public static int process1(int a)
{
    if (a == 0 || a == 1) return 1;

    return process1(a - 1) + process1(a - 2);
}

public static int process2(int n)
{
    if (n == 1) return 1;

    return n * process2(n - 1); // 相同重复逻辑，缩小问题的规模
}

      public static void Permutation(string[] nums, int m, int n)
      {
         string t;
         if (m < n - 1)
         {
            Permutation(nums, m + 1, n);
            for (int i = m + 1; i < n; i++)
            {
               //可抽取Swap方法
               t = nums[m];
               nums[m] = nums[i];
               nums[i] = t;
               Permutation(nums, m + 1, n);

               //可抽取Swap方法
               t = nums[m];
               nums[m] = nums[i];
               nums[i] = t;
            }
         }
         else
         {
                #region 存放到List
                Node root = null;
                Node currentNode;
                for (int j = 0; j < nums.Length; j++)
                {
                    currentNode = new Node(nums[j]);
                    currentNode.nextNode = root;
                    root = currentNode;
                }
                NodeList.Add(root);
                #endregion


                #region  打印控制台
                for (int j = 0; j < nums.Length; j++)
                {
                    Console.Write(nums[j]);
                }
                Console.WriteLine();

                #endregion
         }
      }

      static void Main(string[] args)
      {
         Nums = new string[] { "a", "b", "c" };
         Permutation(Nums, 0, Nums.Length);
         Console.ReadKey();
      }