算法——二分法查找

二分法：

public static int BinarySearch(int[] a, int n, int key)
        {
            int low = 0;
            int high = a.Length - 1;
            int mid;
            while (low <= high)
            {
                mid = (low + high) / 2;
                if (key < a[mid])
                {
                    high = mid - 1;
                }
                else if (key > a[mid])
                {
                    low = mid + 1;
                }
                else
                {
                    return a[mid];
                }
            }
            return 0;
        }

Main

static void Main(string[] args)
        {
            int[] a = new int[] { 10, 25, 35, 40, 60, 61, 90, 110 };
            int result = BinarySearch(a, a.Length,90);
            Console.WriteLine(result);
            Console.ReadKey();
        }