1.6 Image Rotation

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?

将matrix切成4份即可

    public static void imageRotation(int[][] matrix, int n) {
        for (int i = 0; i < n / 2; i++) {
            for (int j = i; j < n - 1 - i; j++) {
                int tmp = matrix[i][j];
                matrix[i][j] = matrix[n - 1 - j][i];
                matrix[n - 1 - j][i] = matrix[n - 1 - i][n - 1 - j];
                matrix[n - 1 - i][n - 1 - j] = matrix[j][n - 1 - i];
                matrix[j][n - 1 - i] = tmp;
            }
        }
    }