算法练习二：二分查找

static void Main(string[] args)
        {
            int[] a=new int[] {1,3,58,654,7,9,11,18,17};
            int c = Serarch(a, 9);

            Console.WriteLine(c);
            Console.ReadLine();
           
            Console.Read();
        }

        static int Serarch(int[] a, int b)
        {
            int low = 0;
            int high = a.Length - 1;
            while(low<=high)
            {

                if (b < a[(high + low )/ 2])
                {
                    high = (high + low) / 2;

                }
                else if (b >a[(high + low) / 2])
                {
                    low = ((high + low)/ 2)+1;
                }
                else if (b ==a[(high + low )/ 2])
                {
                    return ((high + low )/ 2)+1;
                  
                }
            }
            return -1;
        }