Implement Tries in Python

Problem Statement

A trie (pronounced as “try”) or prefix tree is a tree data structure used to efficiently store and retrieve keys in a dataset of strings. There are various applications of this data structure, such as autocomplete and spellchecker.

Implement the Trie class:

• Trie() Initializes the trie object.
• def insert(String word) Inserts the string word into the trie.
• def search(String word) Returns true if the string word is in the trie (i.e., was inserted before), and false otherwise.
• def startsWith(String prefix) Returns true if there is a previously inserted string word that has the prefix prefix, and false otherwise.

Example 1:

Input [“Trie”, “insert”, “search”, “search”, “startsWith”, “insert”, “search”] [[], [“apple”], [“apple”], [“app”], [“app”], [“app”], [“app”]]
Output
[null, null, true, false, true, null, true]

Explanation
Trie trie = new Trie();
trie.insert(“apple”);
trie.search(“apple”); // return True
trie.search(“app”); // return False
trie.startsWith(“app”); // return True
trie.insert(“app”);
trie.search(“app”); // return True

Constraints:
1 <= word.length, prefix.length <= 2000
word and prefix consist only of lowercase English letters.
At most 3 * 104 calls in total will be made to insert, search, and startsWith.

class TrieNode:
    '''
    Not storing the node itself in the TrieNode class. Will be implicit from the HashMap.Example - children["a"] = TrieNode()
    '''
    def __init__(self):
        self.children = {}
        self.endOfWord = False # applicable for every node

class Trie:
    def __init__(self):
        self.root = TrieNode()
    
    def insert(self, word):
        '''
        Insert the word in the tree
        '''
        cur = self.root

        for w in word:
            if not w in cur.children():
                cur.children[w] = TrieNode()
            cur = cur.children[w]
        
        cur.endOfWord = True
    
    def search(self, word):
        cur = self.root

        for w in word:
            if not word in cur.children:
                return False
            cur = cur.children[w]
        return cur.endOfWord
    
    def startsWith(self, prefix):
        cur = self.root

        for p in prefix:
            if not p in cur.children:
                return False
            cur = cur.children[w]
        return True