Mapping numbers to letters
<p>I had an interview question asking this:</p>

<blockquote>
  <p>text file has following lines>  </p>

<pre><code>            1: A C D
            4: A B
            5: D F
            7: A E
            9: B C  
</code></pre>
  
  <p>*Every line has a unique integer followed by a colon and one or
  more letters. These letters are
  delimited spaces (one or more)>  </p>

<pre><code>                            #2 Write a short program in the language
</code></pre>
  
  <p>of your choice that outputs a sorted
  list like</p>

<pre><code>            A: 1 4 7
            B: 4 9
            C: 1 9
            D: 1 5
            E: 7
            F: 5
</code></pre>
</blockquote>

<p>I'm not looking for someone to solve it, but I always get confused with problems like this.  I'd like to do it in C# and was wondering should I store each line in a 2d array?  What is the best way to handle this.  After storing it how do I relist each line with letters rather then numbers?  </p>

<p>Just looking for pointers here.</p>
