title: Is there a well known algorithm fill in the grid given a set of points?
body: <p>I saw this game here <a href="http://apps.microsoft.com/webpdp/en-us/app/flow/117ec8c4-0dab-4536-9bab-2fbecb9583bb" rel="noreferrer">Flow</a>, it looks quite interesting. </p>
  
  <blockquote>
    <p>Connect matching colors with pipe to create a flow. Pair all colors,
    and <strong>cover the entire board</strong> to solve each puzzle. But watch out, pipes
    will break if they cross or overlap.</p>
  </blockquote>
  
  <p>Given a set of pairs <code>(x, y)</code>, is there an algorithm to solve the puzzle, i.e. fill in the whole grid (assuming there is a solution) that I'm not aware of? </p>
  
  <p><img src="https://i.stack.imgur.com/5wwDd.png" alt="enter image description here"></p>