208. Implement Trie (Prefix Tree)

Posted 2020-09-27 Premiumlab

https://leetcode.com/problems/implement-trie-prefix-tree/#/description

 

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

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

 

 

 

Sol: 

 

from collections import defaultdict

class TrieNode(object):
    def __init__(self):
        
        self.nodes = defaultdict(TrieNode)
        self.isword = False



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)
# param_2 = obj.search(word)
# param_3 = obj.startsWith(prefix)