How to prove a cyclic pattern exists in a series of numbers or characters using C#?
<p>This is what I am trying to solve.
I have a series of numbers like </p>

<pre><code>    1 -&gt; 2
    2 -&gt; 3
    3 -&gt; 4
    4 -&gt; 2
    2 -&gt; 1
</code></pre>

<p>I need to write a program to prove if these numbers are points on a graph they form some kind of loop. In the above example 1 -> 2 -> 3 -> 4 -> 2 form a loop.</p>

<p>In the following example there is no loop.</p>

<pre><code>    1 -&gt; 2
    2 -&gt; 3
    3 -&gt; 4
    3 -&gt; 5
</code></pre>

<p>Don't understand how this is a duplicate. Sorry if my question is not clear. I am trying my level best to describe it.
I have set of points/numbers/nodes. They are in pair and also they have direction.
For example pair of numbers are 
        1 -> 2
        2 -> 3
        1 -> 2
        3 -> 4
        4 -> 2
        2 -> 1
        3 -> 4</p>

<p>When these individual nodes are connected from top to bottom I will get linked lists as below
       1 -> 2 -> 3 -> 1 -> 2 -> 3 -> 4 -> 2 -> 1 -> 3 -> 4</p>

<p>I am not looking for a repeated pattern in this set of numbers. trying to find closed loops like 1 -> 2 -> 3 -> 1 is a loop. 2 -> 3 -> 1 -> 2 is a loop. 3 -> 1 -> 2 -> 3, 2 -> 3 -> 4 -> 2,  3 -> 4 -> 2 -> 1 -> 3 etc.
in this wiki link there is one loop that is 1 _. 6 -> 3 -> 1 <a href="http://upload.wikimedia.org/wikipedia/commons/thumb/d/d7/Functional_graph.svg/240px-Functional_graph.svg.png" rel="nofollow">http://upload.wikimedia.org/wikipedia/commons/thumb/d/d7/Functional_graph.svg/240px-Functional_graph.svg.png</a> </p>

<p>Hope this makes the question clear!</p>
