LeetCode #208 Implement Trie (Prefix Tree)

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Trie

Problem

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

Example

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Trie trie = new Trie();

trie.insert("apple");
trie.search("apple");   // returns true
trie.search("app");     // returns false
trie.startsWith("app"); // returns true
trie.insert("app");   
trie.search("app");     // returns true
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class TrieNode:
    def __init__(self):
        self.terminal = False
        self.children = {}

class Trie:

    def __init__(self):
        """
        Initialize your data structure here.
        """
        self.head = TrieNode()

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

        head.terminal = True

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

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

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