class TrieTree():
  def __init__(self):
    self.root = {}
  def addNode(self,str):
    # 树中每个结点(除根节点)，包含到该结点的单词数，以及该结点后面出现字母的键
    nowdict = self.root
    for i in range(len(str)):
      if str[i] not in nowdict:  # 发现新的组合方式
        nowdict[str[i]] = {'count':0,'prefix':str[:i+1]}
      nowdict = nowdict[str[i]]  # 转移到下一个结点
    nowdict['count'] += 1
  def countWord(self,str):
    # 返回输入单词在树中出现的次数
    nowdict = self.root
    for s in str:
      if s not in nowdict:
        return 0
      nowdict = nowdict[s]  # 匹配当前结点,转下一个结点
    # 到了这一步证明单词存在
    return nowdict['count']
if __name__=="__main__":
  pass
  Text = ['b','abc','abd','bcd','abcd','efg','hii','bcd']
  t = TrieTree()
  for str in Text:
    t.addNode(str)
  print t.countWord('bcd')
> 2