new_contents: """Leetcode 394. Decode String
  Medium
  
  URL: https://leetcode.com/problems/decode-string/
  
  Given an encoded string, return its decoded string.
  
  The encoding rule is: k[encoded_string], where the encoded_string inside the 
  square brackets is being repeated exactly k times. 
  Note that k is guaranteed to be a positive integer.
  
  You may assume that the input string is always valid; No extra white spaces, 
  square brackets are well-formed, etc.
  
  Furthermore, you may assume that the original data does not contain any digits and 
  that digits are only for those repeat numbers, k. 
  For example, there won't be input like 3a or 2[4].
  
  Examples:
  s = "3[a]2[bc]", return "aaabcbc".
  s = "3[a2[c]]", return "accaccacc".
  s = "2[abc]3[cd]ef", return "abcabccdcdcdef".
  """
  
  class Solution(object):
      def decodeString(self, s):
          """
          :type s: str
          :rtype: str
          """
          pass
  
  
  def main():
      pass
  
  
  if __name__ == '__main__':
      main()
  
subject: Add lc394_decode_string.py