[Lintcode]Rotate Image

You are given an n x n 2D matrix representing an image.

Rotate the image by 90 degrees (clockwise).

分析：实现题。注意交换元素时坐标计算

public class Solution {
    /**
     * @param matrix: A list of lists of integers
     * @return: Void
     */
    public void rotate(int[][] matrix) {
        int size = matrix.length;
        if(size == 0) return;
        
        for(int i = 0; i < size / 2; i ++) {
            for(int j = i; j < size - i - 1; j++) {
                int tmp = matrix[i][j];
                matrix[i][j] = matrix[j][size - 1 - i];
                matrix[j][size - 1 - i] = tmp;
                
                tmp = matrix[i][j];
                matrix[i][j] = matrix[size - 1 - i][size - 1 - j];
                matrix[size - 1 - i][size - 1 - j] = tmp;
                
                tmp = matrix[i][j];
                matrix[i][j] = matrix[size - 1 - j][i];
                matrix[size - 1 - j][i] = tmp;
            }
        }
    }

}