title: swap two number without using a temporary variable
body: <p>I found this common solution :-</p>
  
  <pre><code>int a=10, b=20;    
  a=a+b;
  b=a-b;
  a=a-b;
  </code></pre>
  
  <p>But what if a=2147483647     the largest value of an integer then probably a=a+b will not be feasible.</p>