rotate-image.md

<p>You are given an <em>n</em> x <em>n</em> 2D matrix representing an image.</p>

<p>Rotate the image by 90 degrees (clockwise).</p>

<p><strong>Note:</strong></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><strong>Example 1:</strong></p>

<pre>
Given <strong>input matrix</strong> = 
[
  [1,2,3],
  [4,5,6],
  [7,8,9]
],

rotate the input matrix <strong>in-place</strong> such that it becomes:
[
  [7,4,1],
  [8,5,2],
  [9,6,3]
]
</pre>

<p><strong>Example 2:</strong></p>

<pre>
Given <strong>input matrix</strong> =
[
  [ 5, 1, 9,11],
  [ 2, 4, 8,10],
  [13, 3, 6, 7],
  [15,14,12,16]
], 

rotate the input matrix <strong>in-place</strong> such that it becomes:
[
  [15,13, 2, 5],
  [14, 3, 4, 1],
  [12, 6, 8, 9],
  [16, 7,10,11]
]
</pre>