函数递归 羊

class Program
    {
        /// <summary>
        /// 每过一个村庄丢失之前的一般还多一只，7个村后还剩下2只
        /// </summary>
        /// <param name="cun"></param>
        /// <returns></returns>
        public int yangshu(int cun)
        {
            int sum = 0;
            if (cun==7)
            {
                sum = 2;
                return sum;
            }
            sum = (yangshu(cun + 1) + 1) * 2;//5天为例：sum=(yangshu(cun+1)+1)*2→sum=(yangshu(5+1)+1)*2→sum=((yangshu(6+1)+1)*2+1)*2
            return sum;//yangshu(5+1)=(yangshu(6+1)+1)*2
        }
        static void Main(string[] args)
        {
            int sum = new Program().yangshu(0);
            Console.WriteLine(sum);
            Console.ReadLine();
        }
    }