Rotate Image
<p>You are given an <code>n x n</code> 2D <code>matrix</code> representing an image, rotate the image by <strong>90</strong> degrees (clockwise).</p>

<p>You have to rotate the image <a href="https://en.wikipedia.org/wiki/In-place_algorithm" target="_blank"><strong>in-place</strong></a>, which means you have to modify the input 2D matrix directly. <strong>DO NOT</strong> allocate another 2D matrix and do the rotation.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/solution/0000-0099/0048.Rotate%20Image/images/mat1.jpg" style="width: 500px; height: 188px;" />
<pre>
<strong>Input:</strong> matrix = [[1,2,3],[4,5,6],[7,8,9]]
<strong>Output:</strong> [[7,4,1],[8,5,2],[9,6,3]]
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/solution/0000-0099/0048.Rotate%20Image/images/mat2.jpg" style="width: 500px; height: 201px;" />
<pre>
<strong>Input:</strong> matrix = [[5,1,9,11],[2,4,8,10],[13,3,6,7],[15,14,12,16]]
<strong>Output:</strong> [[15,13,2,5],[14,3,4,1],[12,6,8,9],[16,7,10,11]]
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>n == matrix.length == matrix[i].length</code></li>
	<li><code>1 &lt;= n &lt;= 20</code></li>
	<li><code>-1000 &lt;= matrix[i][j] &lt;= 1000</code></li>
</ul>
Array; Math; Matrix
public class Solution {
    public void Rotate(int[][] matrix) {
        int n = matrix.Length;
        for (int i = 0; i < n >> 1; ++i) {
            for (int j = 0; j < n; ++j) {
                int t = matrix[i][j];
                matrix[i][j] = matrix[n - i - 1][j];
                matrix[n - i - 1][j] = t;
            }
        }
        for (int i = 0; i < n; ++i) {
            for (int j = 0; j < i; ++j) {
                int t = matrix[i][j];
                matrix[i][j] = matrix[j][i];
                matrix[j][i] = t;
            }
        }
    }
}
