折半插入排序

        /// <summary>
        /// 折半插入排序
        /// </summary>
        /// <param name="arr"></param>
        /// <returns></returns>
        public static int[] HalfInsertSort(int[] arr)
        {
            for (int i = 1; i < arr.Length; i++)
            {
                if (arr[i] >= arr[i - 1])
                    continue;
                int low = 0;
                int high = i - 1; 
                int temp = arr[i];
                int j = i;

                //二分法查找插入点
                while (low <= high)
                {
                    int mid = (low + high) / 2; //中点在low
                    if (temp > arr[mid])
                        low = mid + 1;
                    else if (temp < arr[mid])
                        high = mid - 1;
                    else
                        break;
                }

                //移动位置
                while(j > low)  //low == high，arr[low]即为插入点
                {
                    arr[j] = arr[j - 1];
                    --j;
                }
                arr[j] = temp;
            }
            return arr;
        }