C#算法小程序（1）

两个数组a1,a2,找到a1中第一次出现a2的元素下表：

class Program
    {
        static void Main(string[] args)
        {
            int[] a1 = { 4, 3, 7, 6, 9, 5, 7, 6, 4 };
            int[] a2 = { 7, 6 };

            int result = GetFirst(a1, a2);
            Console.WriteLine(result);
            Console.ReadKey();
        }

        private static int GetFirst(int[] a1, int[] a2)
        {
            int first = -1;
            int a1length = a1.Length;
            int a2length = a2.Length;
            bool tag = true;
            for (int i = 0; i < a1length; i++)
            {
                if (a1[i] == a2[0])
                {
                    for (int j = 1; j < a2length; j++)
                    {
                        if (a2[j] != a1[i + j])
                        {
                            tag = false;
                        }
                    }
                    if (tag == true)
                    {
                        first = i;
                        break;
                    }
                }
            }
            return first;
        }
    }
}