208. Implement Trie (Prefix Tree).py

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

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

# Use Dict to solve this problem
from collections import defaultdict
class TrieNode(object):
    def __init__(self):
        """
        Initialize your data structure here.
        """
        self.nodes = defaultdict(TrieNode)  # Easy to insert new node.
        self.isword = False  # True for the end of the trie.

    def __repr__(self):
        return repr(self.nodes)


class Trie(object):

    def __init__(self):
        """
        Initialize your data structure here.
        """
        self.root = TrieNode()        

    def insert(self, word):
        """
        Inserts a word into the trie.
        :type word: str
        :rtype: void
        """
        curr = self.root
        for char in word:
            curr = curr.nodes[char]
        curr.isword = True
        

    def search(self, word):
        """
        Returns if the word is in the trie.
        :type word: str
        :rtype: bool
        """
        curr = self.root
        for char in word:
            if char not in curr.nodes:
                return False
            curr = curr.nodes[char]
        return curr.isword        

    def startsWith(self, prefix):
        """
        Returns if there is any word in the trie that starts with the given prefix.
        :type prefix: str
        :rtype: bool
        """
        curr = self.root
        for char in prefix:
            if char not in curr.nodes:
                return False
            curr = curr.nodes[char]
        return True
        


# Your Trie object will be instantiated and called as such:
obj = Trie()
obj.insert('word')
print obj.root
# param_2 = obj.search(word)
# param_3 = obj.startsWith(prefix)