title: Puzzle: find the minimum number of weights
body: <p>I came across this question: say given two weights 1 and 3, u can weigh 1,2 (by 3-1),3,4 (by 3+1) (using both sides of balance). Now find the minimum number of weights so that you can measure 1 to 1000.</p>
  
  <p>So the answer was 1,3,9,27...</p>
  
  <p>I want to know how do you arrive at such a solution means powers of 3. What is the thought process?</p>
  
  <p>Source: <a href="http://classic-puzzles.blogspot.com/search/label/Google%20Interview%20Puzzles" rel="nofollow noreferrer">http://classic-puzzles.blogspot.com/search/label/Google%20Interview%20Puzzles</a></p>
  
  <p>Solution: <a href="http://classic-puzzles.blogspot.com/2006/12/solution-to-shopkeeper-problem.html" rel="nofollow noreferrer">http://classic-puzzles.blogspot.com/2006/12/solution-to-shopkeeper-problem.html</a></p>