Implement Trie

Implement a trie withinsert,search, andstartsWithmethods.

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

Some more points (combining from geekforgeeks and stack overflow):

Trie s an efficient information re_trie_val data structure. Using trie, search complexities can be brought to optimal limit (key length).

If we store keys in binary search tree, a well balanced BST will need time proportional to

M * log N

, where M is maximum string length and N is number of keys in tree. Using trie, we can search the key in O(N * M) time. Since you need to create all the N*M nodes at least once. However the penalty is on trie storage requirements.

class TrieNode(object):
    def __init__(self):
        """
        Initialize your data structure here.
        """
        self.word = False
        self.children = {}


class Trie(object):

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

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


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


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


# Your Trie object will be instantiated and called as such:
# trie = Trie()
# trie.insert("somestring")
# trie.search("key")

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class TrieNode(object): def __init__(self): """ Initialize your data structure here. """ self.word = False self.children = {} class Trie(object): def __init__(self): self.root = TrieNode() def insert(self, word): """ Inserts a word into the trie. :type word: str :rtype: void """ node = self.root for ch in word: if ch not in node.children: node.children[ch] = TrieNode() node = node.children[ch] node.word = True def search(self, word): """ Returns if the word is in the trie. :type word: str :rtype: bool """ node = self.root for ch in word: if ch not in node.children: return False node = node.children[ch] return node.word def startsWith(self, prefix): """ Returns if there is any word in the trie that starts with the given prefix. :type prefix: str :rtype: bool """ node = self.root for ch in prefix: if ch not in node.children: return False node = node.children[ch] return True # Your Trie object will be instantiated and called as such: # trie = Trie() # trie.insert("somestring") # trie.search("key")