Rotate images by 90 degrees in place.

gistfile1.java

package questions;

public class Questions1_6 {

    public static void main(String[] args) {
        // initialize matrix
        final int N = 10;
        int[][] matrix = new int[N][N];
        for (int i = 0; i < N; i++) {
            for (int j = 0; j < N; j++) {
                matrix[i][j] = i * 10 + j;
            }
        }
        
        showMatrix(matrix);
        System.out.print("\n");
        rotateMatrix(matrix);
        System.out.print("\n");
        showMatrix(matrix);
    }

    public static void rotateMatrix(int[][] matrix) {
        int N = matrix.length - 1;

        for (int r = 0; r <= N / 2; r++) {
            for (int x = 0; x < N - 2 * r; x++) {
                int tmp = matrix[r + x][r];
                matrix[r + x][r] = matrix[r][N - x - r];
                matrix[r][N - x - r] = matrix[N - x - r][N - r];
                matrix[N - x - r][N - r] = matrix[N - r][r + x];
                matrix[N - r][r + x] = tmp;
            }
        }
    }

    public static void showMatrix(int[][] matrix) {
        for (int i = 0; i < matrix.length; i++) {
            for (int j = 0; j < matrix[i].length; j++) {
                System.out.print(String.format("%02d", matrix[j][i]) + ' ');
            }
            System.out.print("\n");
        }
    }
}