You are given an n x n 2D matrix representing an image.
Rotate the image by 90 degrees (clockwise).
Follow up:
Could you do this in-place?
解题思路：
找规律即可，JAVA实现如下：
static public void rotate(int[][] matrix) {
int[][] matrixArray=new int[matrix.length][matrix[0].length];
for(int i=0;i<matrix.length;i++)
System.arraycopy(matrix[i], 0, matrixArray[i], 0, matrix[i].length);
for(int i=0;i<matrix.length;i++)
for(int j=0;j<matrix.length;j++)
matrix[i][j]=matrixArray[matrix.length-j-1][i];
}