new_contents: #!/usr/bin/env python
  # encoding: utf-8
  
  """
  minimum-depth-of-binary-tree.py
   
  Created by Shuailong on 2016-02-25.
  
  https://leetcode.com/problems/minimum-depth-of-binary-tree/.
  
  """
  
  # Definition for a binary tree node.
  class TreeNode(object):
      def __init__(self, x):
          self.val = x
          self.left = None
          self.right = None
  
  class Solution(object):
      def minDepth(self, root):
          """
          :type root: TreeNode
          :rtype: int
          """
          if root is None:
              return 0
          if root.left is None and root.right is None:
              return 1
          if root.left is None:
              return self.minDepth(root.right) + 1
          if root.right is None:
              return self.minDepth(root.left) + 1
          return min(self.minDepth(root.left), self.minDepth(root.right)) + 1
  
          
  
  def main():
  
      n1 = TreeNode(6)
      n2 = TreeNode(4)
      n3 = TreeNode(10)
      n4 = TreeNode(1)
      n5 = TreeNode(7)
      n6 = TreeNode(100)
      n7 = TreeNode(80)
      n8 = TreeNode(30)
  
      root = n1
      n1.left = n2
      n1.right = n3
      n2.left = n4
      n3.left = n5
      n3.right = n6
      n6.left = n7
      n7.left = n8
  
      solution = Solution()
      print solution.minDepth(root)
      
  if __name__ == '__main__':
      main()
  
          
subject: solve 1 problem