odd-even-linked-list.md

<p>Given a singly linked list, group all odd nodes together followed by the even nodes. Please note here we are talking about the node number and not the value in the nodes.</p>

<p>You should try to do it in place. The program should run in O(1) space complexity and O(nodes) time complexity.</p>

<p><b>Example 1:</b></p>

<pre>
<strong>Input: </strong><code>1-&gt;2-&gt;3-&gt;4-&gt;5-&gt;NULL</code>
<strong>Output: </strong><code>1-&gt;3-&gt;5-&gt;2-&gt;4-&gt;NULL</code>
</pre>

<p><b>Example 2:</b></p>

<pre>
<strong>Input: </strong>2<code>-&gt;1-&gt;3-&gt;5-&gt;6-&gt;4-&gt;7-&gt;NULL</code>
<strong>Output: </strong><code>2-&gt;3-&gt;6-&gt;7-&gt;1-&gt;5-&gt;4-&gt;NULL</code>
</pre>

<p><b>Note:</b></p>

<ul>
	<li>The relative order inside both the even and odd groups should remain as it was in the input.</li>
	<li>The first node is considered odd, the second node even and so on ...</li>
</ul>