Trie

Fatma Kahveci
Coding
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  • A type of tree

  • It stores characters.

  • Don’t look up each prefix from the root.

    • Build on past calls.

  • You can implement it by keeping the state within a tree and return Node reference

class TrieNode:
    def __init__(self):
        self.children = {}
        self.end_of_trie = False

class Trie:
    def __init__(self):
        self.root = TrieNode()
    
    def insert(self, word:str) -> None:
        curr = self.root
        for ch in word:
            if ch not in curr.children:
                curr.children[ch] = TrieNode()
            curr = curr.children[ch]
        curr.end_of_trie = True
    
    def search(self, word: str) -> bool:
        curr = self.root
        for ch in word:
            if ch not in curr.children:
                return False
            curr = curr.children[ch]
        return curr.end_of_trie
    
    def startsWith(self, prefix: str) -> bool:
        curr = self.root
        for ch in prefix:
            if ch not in curr.children:
                return False
            curr = curr.children[ch]
        return True