new_contents: """Leetcode 286. Walls and Gates (Premium)
  Medium
  
  URL: https://leetcode.com/problems/walls-and-gates/
  
  You are given a m x n 2D grid initialized with these three possible values.
  -1 - A wall or an obstacle.
  0 - A gate.
  INF - Infinity means an empty room. We use the value 231 - 1 = 2147483647 to
  represent INF as you may assume that the distance to a gate is less than 2147483647.
   
  Fill each empty room with the distance to its nearest gate.
  If it is impossible to reach a gate, it should be filled with INF.
  
  For example, given the 2D grid:
  INF  -1  0  INF
  INF INF INF  -1
  INF  -1 INF  -1
  0  -1 INF INF
  
  After running your function, the 2D grid should be:
  3  -1   0   1
  2   2   1  -1
  1  -1   2  -1
  0  -1   3   4
  """
  
  class Solution(object):
      def wallsAndGates(self, rooms):
          """
          :type rooms: List[List[int]]
          :rtype: void Do not return anything, modify rooms in-place instead.
          """
          pass
  
  
  def main():
      pass
  
  
  if __name__ == '__main__':
      main()
  
subject: Add lc0286_walls_and_gates.py