LeetCode OJ-48-Rotate Image

题目：

You are given an n x n 2D matrix representing an image.
Rotate the image by 90 degrees (clockwise).

大意：

n×n二维矩阵顺时针旋转90°，求旋转后的数组。

思路：

找到 matrix[i][j] = matrix[n-1-j][i] 的规律。

代码：

public class Solution {    public void rotate(int[][] matrix) {        int n = matrix.length;        for (int i = 0; i < n / 2; i++) {            for (int j = 0; j < Math.ceil(((double) n) / 2.); j++) {                int temp = 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] = temp;            }        }    }}