旋转二维数组

 

    /// <summary>
    /// Q:Given an image represented by an NxN matrix, where each pixel in the image is 4 bytes,
    /// write a method to rotate the image by 90 degrees. Can you do this in place?
    /// </summary>
    class Program
    {
        static void Main(string[] args)
        {
            Program p = new Program();
            int[,] matrix = new int[3, 4] { { 1, 2, 3, 4 }, { 5, 6, 7, 8 }, { 9, 10, 11, 12 } };
            int[,] matrix2 = new int[4, 4] { { 1, 1, 1, 1 }, { 2, 2, 2, 2 }, { 3, 3, 3, 3 },{4,4,4,4} };
            int[,] matrix3 = new int[4, 4] { { 1, 2, 3, 4 }, { 1, 2, 3, 4 }, { 1, 2, 3, 4 }, { 1, 2, 3, 4 } };
            int[,] matrix4 = new int[3,3] { { 1, 2, 3 }, { 4,5,6 }, { 7,8,9 } };
            int[,] matrix5 = new int[4, 4] { { 1, 2, 3,4 }, { 5,6,7,8 }, { 9,10,11,12 },{13,14,15,16} };
            int[,] matrix6 = new int[3, 2] { { 1, 2}, { 3,4},{5,6} };
            int[,] result = p.RotateMatrixWith90Degree(matrix);
            result = p.RotateMatrixWith90DegreeInHour(matrix);
            PrintMatrix(matrix5);
            p.RotateMatrixWith90DegreeInPlace(ref matrix5);
            PrintMatrix(matrix5);
            int[,] t = (int[,])ResizeMultipleDimensionArray(matrix6, new int[] { 2,3});
            PrintMatrix(t);
            Console.ReadKey();
        }

        /// <summary>
        /// 第一种方法，很自然想到定义一个新的数组, 旋转后的元素存在新数组中
        /// 该方法不受矩阵形状限制，可以是非方形矩阵
        /// </summary>
        public int[,] RotateMatrixWith90Degree(int[,] matrix)
        {
            int line = matrix.GetLength(0);
            int column = matrix.GetLength(1);
            if (line == 0 || column == 0)
            {
                throw new ArgumentNullException("matrix is empty,either its line or column length is 0");
            }

            int[,] newMatrix = new int[column, line];
            for (int i = 0;i< line; i++)
            {
                for (int j = 0; j < column; j++)
                {
                    newMatrix[j, line-i-1] = matrix[i, j];
                }
            }
            return newMatrix;
        }

        /// <summary>
        /// 逆时针旋转90度
        /// </summary>
        public int[,] RotateMatrixWith90DegreeInHour(int[,] matrix)
        {
            int line = matrix.GetLength(0);
            int column = matrix.GetLength(1);
            if (line == 0 || column == 0)
            {
                throw new ArgumentNullException("matrix is empty,either its line or column length is 0");
            }

            int[,] newMatrix = new int[column, line];
            for (int i = 0; i < line; i++)
            {
                for (int j = 0; j < column; j++)
                {
                    newMatrix[column-j-1, i] = matrix[i, j];
                }
            }
            return newMatrix;
        }

        /// <summary>
        /// in-place旋转
        /// 假设条件：方形矩阵
        /// </summary>
        public void RotateMatrixWith90DegreeInPlace(ref int[,] matrix)
        {
            int line = matrix.GetLength(0);
            int column = matrix.GetLength(1);
            if (line == 0 || column == 0)
            {
                throw new ArgumentNullException("matrix is empty,either its line or column length is 0");
            }
            else if(line!=column)
            {
                throw new ArgumentException("matrix is not N*N");
            }
            for (int i = 0; i < line/2; i++)
            {
                for (int j = i; j < line-1-i; j++)
                {
                    int lefttop = matrix[i, j];
                    matrix[i, j] = matrix[line - j - 1,i];
                    matrix[line - j - 1, i] = matrix[line - i - 1, line - j - 1];
                    matrix[line - i - 1, line - j - 1] = matrix[j, line - i - 1];
                    matrix[j, line - i - 1] = lefttop;
                }
            }
        }

        public static Array ResizeMultipleDimensionArray(Array arr, int[] newSizes)
        {
            Array newArr=Array.CreateInstance(arr.GetType().GetElementType(), newSizes);
            int length = arr.Length < newArr.Length ? arr.Length : newArr.Length;
            Array.ConstrainedCopy(arr, 0, newArr, 0, length);
            return newArr;
        }

        /// <summary>
        /// Print the matrix to console
        /// </summary>
        public static void PrintMatrix(int[,] matrix)
        {
            int line = matrix.GetLength(0);
            int column = matrix.GetLength(1);
            if (line == 0 || column == 0)
            {
                Console.WriteLine("empty array!");
            }
            else
            {
                Console.WriteLine("lines:" + line.ToString());
                Console.WriteLine("columns:" + column.ToString());
            }
            for (int i = 0; i < line; i++)
            {
                Console.WriteLine();
                for (int j = 0; j < column; j++)
                {
                    Console.Write(matrix[i, j].ToString().PadLeft(5));
                    Console.Write(" ");
                }
            }
        }
    }