trie.py

class TrieNode:
    def __init__(self):
        """Node objects within trie
        """
        self.children = {}
        self.is_word = False
        

class Trie:

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

    def insert(self, word):
        """
        Inserts a word into the trie.
        :type word: str
        :rtype: void
        """
        curr_node = self.root
        for c in word:
            try:
                curr_node = curr_node.children[c]
            except:
                curr_node.children[c] = TrieNode()
                curr_node = curr_node.children[c]
        curr_node.is_word = True
        
    def search(self, word):
        """
        Returns if the word is in the trie.
        :type word: str
        :rtype: bool
        """
        curr_node = self.root
        for c in word:
            try:
                curr_node = curr_node.children[c]
            except KeyError:
                return False
        return curr_node.is_word

    def starts_with(self, prefix):
        """
        Returns if there is any word in the trie
        that starts with the given prefix.
        :type prefix: str
        :rtype: bool
        """
        curr_node = self.root
        for c in prefix:
            try:
                curr_node = curr_node.children[c]
            except KeyError:
                return False
        return True
        
        
if __name__ == '__main__':
    trie = Trie()
    trie.insert("somestring")
    trie.search("key")