CareerCup_1.6 - Matrix Rotation

MartrixRotation.java

package Chapter1;

import java.util.Random;

public class MartrixRotation {
    public static void rotateClockWise(int[][] matrix) {
	if (matrix == null || matrix.length <= 1)
	    return;
	int N = matrix.length; // NxN matrix
	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;
	    }
	}
    }

    public static void print(int[][] matrix) {
	for (int i = 0; i < matrix.length; i++) {
	    for (int j = 0; j < matrix[0].length; j++) {
		System.out.print(matrix[i][j] + " ");
	    }
	    System.out.println();
	}
    }

    public static void randomInit(int[][] matrix) {
	Random r = new Random();
	for (int i = 0; i < matrix.length; i++) {
	    for (int j = 0; j < matrix[0].length; j++) {
		matrix[i][j] = Math.abs(r.nextInt() % 1001);
	    }
	}
    }

    public static void main(String[] args) {
	int[][] mat = new int[5][5];
	randomInit(mat);
	print(mat);
	System.out.println();
	rotateClockWise(mat);
	print(mat);
    }
}