题解一：

        翻转数组：先将数组沿右上-左下对角线翻转，再将数组上下翻转。

class Solution {
    public void rotate(int[][] matrix) {
        int n = matrix.length;
        for (int i = 0; i < n; i++) {//沿右上-左下对角线翻转
            for (int j = 0; j < n - i - 1; j++) {
                int temp = matrix[i][j];
                matrix[i][j] = matrix[n - j - 1][n - i - 1];
                matrix[n - j - 1][n - i - 1] = temp;
            }
        }

        for (int i = 0; i < n / 2; i++) {//沿上下翻转
            for (int j = 0; j < n; j++) {
                int temp = matrix[i][j];
                matrix[i][j] = matrix[n - i - 1][j];
                matrix[n - i - 1][j] = temp;
            }
        }
    }
}