LeetCode----Implement Trie (Prefix Tree)

Implement Trie (Prefix Tree)

Implement a trie with insert, search, and startsWith methods.

Note:
You may assume that all inputs are consist of lowercase letters a-z.

分析：

实现Tire树的几个函数。

Python下的实现可以在TireNode中使用字典存储关键字，既减少存储空间，也方便查找，其次，也就不需要将字母转换成对应的数字表示其值了。

代码：

class TrieNode(object):
    def __init__(self):
        """
        Initialize your data structure here.
        """
        self.tnlst = {}
        # self.count = 1
        self.terminal = False


class Trie(object):

    def __init__(self):
        self.root = TrieNode()

    def insert(self, word):
        """
        Inserts a word into the trie.
        :type word: str
        :rtype: void
        """
        r = self.root
        for w in word:
            if w not in r.tnlst:
                r.tnlst[w] = TrieNode()
            r = r.tnlst[w]
        r.terminal = True

    def search(self, word):
        """
        Returns if the word is in the trie.
        :type word: str
        :rtype: bool
        """
        r = self.root
        for w in word:
            if w in r.tnlst:
                r = r.tnlst[w]
            else:
                return False
        return r.terminal

    def startsWith(self, prefix):
        """
        Returns if there is any word in the trie
        that starts with the given prefix.
        :type prefix: str
        :rtype: bool
        """
        r = self.root
        for w in prefix:
            if w in r.tnlst:
                r = r.tnlst[w]
            else:
                return False
        return True