Which is better searching in string or array
<p>I need to store certain id's , and check if one exists there.<br>
Either i can use concatenated string or array/List, which of them is a better and faster way.
This is how actually data is organized :<br></p>

<ul>
<li>Year 1
   <ul><li>Month 1
           <ul>
              <li>Day 1</li>
              <li>Day 2</li>
              <li>Day 3</li>
           </ul>
       </li>
     <li>Month 2
           <ul>
              <li>Day 6</li>
              <li>Day 2</li>
              <li>Day 3</li>
           </ul>
       </li>

   </ul>
</li>


<li>Year 2
   <ul><li>Month 3
           <ul>
              <li>Day 1</li>
              <li>Day 3</li>
              <li>Day 7</li>
           </ul>
       </li>
     <li>Month 6
           <ul>
              <li>Day 6</li>
              <li>Day 2</li>
              <li>Day 3</li>
           </ul>
       </li>

   </ul>
</li>

</ul>
