1.一列数的规则如下: 1、1、2、3、5、8、13、21、34...... 求第30位数是多少， 用递归算法实现。
public class TuZi
    {
        public int TZ(int x)
        {
            if (x == 1 || x == 2)
            {
                return 1;
            }
            else
            {
                return TZ(x - 1) + TZ(x - 2);
            }
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            TuZi a = new TuZi();
            Console.WriteLine(a.TZ(12));
        }
    }


2.遍历页面上所有的textbox页面并将它赋值为string.empty?
foreach (System.Windows.Forms.Control item in this.Controls)
            {
                if (item is System.Windows.Forms.TextBox)
                {
                    System.Windows.Forms.TextBox tb = (System.Windows.Forms.TextBox)item;
                    tb.Text = string.Empty;
                }
            }
control类是所有控件的基类

3.实现一个冒泡排序算法
int[] arr = { 10, 29, 30, 40, 5 };
            for (int i = arr.Length; i >= 2;i-- )
            {
                for (int j = 0; j <i - 1;j++ )
                {
                    if (arr[j] < arr[j + 1])
                    {
                        int temp = arr[j + 1];
                        arr[j + 1] = arr[j];
                        arr[j] = temp;                  
                    }              
                }   
            }
            foreach (int item in arr)
            {
                Console.Write(item+" ");
                
            }
            Console.Read();

递归、遍历、冒泡