text: import re
  class Solution(object):
      def decodeString(self, s):
          """
          :type s: str
          :rtype: str
          """
          groups = s.count('[')
          for _group in range(groups):
              match = re.search(r'(\d*)\[(\w*)\]', s)
              times = int(match.group(1))
              letters = match.group(2)
              s = s.replace(match.group(0), letters*times)
          return s
  