title: What data structure would be best to check if value is between a and b defining block boundaries
body: <p>I have the following table:</p>
  
  <p>block |  start | end </p>
  
  <blockquote>
    <p>1     |  1   |   4</p>
    
    <p>2     |    5  |     9</p>
    
    <p>3     |    10 |     20</p>
    
    <p>4     |   21  |    50</p>
    
    <p>..........</p>
    
    <p>n     |    1000 |   2000</p>
  </blockquote>
  
  <p>When given a value to variable c i have to search which block contains c (  start &lt; c &lt; end ). For example when c = 1001, c is in block n.
  What data structure would be the most efficient?</p>