title: Interview question: Create an object oriented design for Sudoku
body: <p>I answered that I will have have a 2d Array.</p>
  
  <p>And then I will have 3 functions</p>
  
  <ul>
  <li>one to check the horizontal condition.</li>
  <li>another function to check vertical condition</li>
  <li>and another one the check the 3*3 block condition.</li>
  </ul>
  
  <hr>
  
  <p>But he is not satisfied, can any one give a good answer for this question?</p>
  
  <p>I found this stack overflow link related to my question. 
  <a href="https://stackoverflow.com/questions/431996/programming-design-help-how-to-structure-a-sudoku-solver-program">Programming Design Help - How to Structure a Sudoku Solver program?</a>.</p>
  
  <p>But I want a proper object oriented design (like what should be the classes, inheritance and other details) which are the same things interviewer expected from me.</p>