title: Correctness of Sakamoto's algorithm to find the day of week
body: <p>I am using Sakamoto's algorithm to find out the day of week from a given date.
  Can anybody tell me the correctness of this algorithm? I just want this from 2000 to 2099.</p>
  
  <p>The algorithm from <a href="http://en.wikipedia.org/wiki/Determination_of_the_day_of_the_week" rel="noreferrer">Wikipedia</a> is given for reference.</p>
  
  <pre><code>int dow(int y, int m, int d)
  {
     static int t[] = {0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4};
     y -= m &lt; 3;
     return (y + y/4 - y/100 + y/400 + t[m-1] + d) % 7;
  }
  </code></pre>