LeetCode 图解 | 48 . 旋转图像

给定 matrix = 
[
  [1,2,3],
  [4,5,6],
  [7,8,9]
],

原地旋转输入矩阵，使其变为:
[
  [7,4,1],
  [8,5,2],
  [9,6,3]
]

给定 matrix =
[
  [ 5, 1, 9,11],
  [ 2, 4, 8,10],
  [13, 3, 6, 7],
  [15,14,12,16]
], 

原地旋转输入矩阵，使其变为:
[
  [15,13, 2, 5],
  [14, 3, 4, 1],
  [12, 6, 8, 9],
  [16, 7,10,11]
]

class Solution {
    public void rotate(int[][] matrix) {
        int N = matrix.length;
        for (int i = 0; i < N/2; i++) {
            for (int j = 0; j < (N+1)/2; j++) {
                int t = 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] = t;
            }
        }
    }
}