title: Minimum time required to clean all the dirty points
body: <p>Consider points on a line on the x-axis starting from 0 towards a positive direction.<br />
  There are N people standing on some points and there are M points that are dirty<br />
  I need to find out the minimum time required to clean all the dirty points.<br />
  At each second each person can move on point in any direction left or right or can stay<br />
  When a person comes to a dirty point the point gets cleaned</p>
  <p><strong>Example:</strong><br />
  Consider person on [5,10] and dirty = [8] mean person is at point 5 and 10 and point 8<br />
  is the dirty point. The second person can go to point 8 and clean it. This will require 2 seconds</p>
  <p>Consider [100,300] and dirty = [200,400] the first person could go from point 100 to point<br />
  200 and at the same time the second person could go from point 300 to 400<br />
  This will take 100 seconds.</p>
  <p>Not sure how to approach it. Could one follow the greedy approach and simply move towards<br />
  the point that is closest. But then what if there are two points that are closest</p>