排序與查詢演算法有很多種，我們不必全部記住它，只需記住最快的方法就好了（當然，你也可以用c#自帶的方法或者Linq，這不在本文討論之列）

直接上程式碼：

        /// <summary>
        /// 折半查詢
        /// </summary>
        /// <param name="dDataList"></param>
        /// <param name="data"></param>
        /// <returns></returns>
        public static int BinarySearch(List<int> dDataList, int data, int low, int high)
        {
            int mid = (low + high) / 2;
            if (dDataList[mid] == data)
                return mid;
            if (low > high)
                return -1;

            if (data < dDataList[mid])
                return BinarySearch(dDataList, data, low, mid - 1);
            else
                return BinarySearch(dDataList, data, mid + 1, high);
        }
 

        /// <summary>
        /// 快速排序
        /// </summary>
        /// <param name="dDataList"></param>
        /// <param name="low"></param>
        /// <param name="high"></param>
        public static void QuickSort(ref List<int> dDataList, int low, int high)
        {
            if (low >= high)
                return;

            int temp = dDataList[low];//以a[low]為樞紐值
            int i = low, j = high;
            //一趟快速排序
            while (i < j)
            {//雙向掃描
                while (i < j && dDataList[j] >= temp)
                    j--;
                dDataList[i] = dDataList[j];
                while (i < j && dDataList[i] <= temp)
                    i++;
                dDataList[j] = dDataList[i];
            }
            dDataList[i] = temp;//放置樞紐值
            //分別對左邊、右邊排序
            QuickSort(ref dDataList, low, i - 1);
            QuickSort(ref dDataList, i + 1, high);
        }