old_contents: """Leetcode 149. Max Points on a Line
  Hard
  
  URL: https://leetcode.com/problems/max-points-on-a-line/
  
  Given n points on a 2D plane, find the maximum number of points that
  lie on the same straight line.
  
  Example 1:
  Input: [[1,1],[2,2],[3,3]]
  Output: 3
  Explanation:
  ^
  |
  |        o
  |     o
  |  o  
  +------------->
  0  1  2  3  4
  
  Example 2:
  Input: [[1,1],[3,2],[5,3],[4,1],[2,3],[1,4]]
  Output: 4
  Explanation:
  ^
  |
  |  o
  |     o        o
  |        o
  |  o        o
  +------------------->
  0  1  2  3  4  5  6
  
  NOTE: input types have been changed on April 15, 2019.
  Please reset to default code definition to get new method signature.
  """
  
  class Solution(object):
      def maxPoints(self, points):
          """
          :type points: List[List[int]]
          :rtype: int
          """
          pass
  
  
  def main():
      pass
  
  
  if __name__ == '__main__':
      main()
  
new_contents: """Leetcode 149. Max Points on a Line
  Hard
  
  URL: https://leetcode.com/problems/max-points-on-a-line/
  
  Given n points on a 2D plane, find the maximum number of points that
  lie on the same straight line.
  
  Example 1:
  Input: [[1,1],[2,2],[3,3]]
  Output: 3
  Explanation:
  ^
  |
  |        o
  |     o
  |  o  
  +------------->
  0  1  2  3  4
  
  Example 2:
  Input: [[1,1],[3,2],[5,3],[4,1],[2,3],[1,4]]
  Output: 4
  Explanation:
  ^
  |
  |  o
  |     o        o
  |        o
  |  o        o
  +------------------->
  0  1  2  3  4  5  6
  
  NOTE: input types have been changed on April 15, 2019.
  Please reset to default code definition to get new method signature.
  """
  
  class Solution(object):
      def _gcd(self, m, n):
          """Greatest common divisor."""
          if n == 0:
              return m
          return self._gcd(n, m % n)
  
      def maxPoints(self, points):
          """
          :type points: List[List[int]]
          :rtype: int
          """
          pass
  
  
  def main():
      pass
  
  
  if __name__ == '__main__':
      main()
  
subject: Implement gcd()