Trie Implementation - A way to search for strings and prefixes given a list of strings

trie.py

class Node:
    def __init__(self, key=None, word_count=0):
        self.key = key
        self.word_count = word_count #Since word and prefix counts are same
        self.edges = [] #List of Nodes

class Trie:
    def __init__(self, root=None):
        self.root = root

    def add(self, word, node):

        if len(word) == 0:
            return
        edge = filter(lambda w: w.key == word[0], node.edges) 
        if len(edge) > 0:
            edge[0].word_count +=1
            self.add(word[1:], edge[0]) #Add the suffix excluding the first
        else:
            #Word not found
            next = Node(key=word[0], word_count=1)
            node.edges.append(next)
            
            self.add(word[1:], node.edges[-1])

    def find(self, word, node):

        if len(word) == 0:
            return 0

        edge = filter(lambda w: w.key == word[0], node.edges)
        if len(edge) > 0:
            if len(word) == 1:
                return edge[0].word_count
            else:
                return self.find(word[1:], edge[0])
        else:
            return 0



trie = Trie(root=Node())


def add(word):
    trie.add(word, trie.root)

def find(word):
    print trie.find(word, trie.root)

n = int(raw_input().strip())
for a0 in xrange(n):
    op, contact = raw_input().strip().split(' ')
    if op == "add":
        add(contact)
    else:
        find(contact)

trie_input_1.txt

4
add hack
add hackerrank
find hac
find hak

trie_output_1.txt

2
2