python数据结构与算法——字典树

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