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class Trie {
private:
    vector<Trie*> child;
    bool is_end;
public:
    Trie(): child(26), is_end(false) {}
    
    Trie* searchPrefix(string prefix) {
        Trie* node = this;
        for (char ch : prefix) {
            ch -= 'a';
            if (node->child[ch] == nullptr) {
                return nullptr;
            }
            node = node->child[ch];
        }
        return node;
    }

    void insert(string word) {
        Trie* node = this;
        for (char ch : word) {
            ch -= 'a';
            if (node->child[ch] == nullptr) {
                node->child[ch] = new Trie();
            }
            node = node->child[ch];
        }
        node->is_end = true;
    }
    
    bool search(string word) {
        Trie* node = searchPrefix(word);
        return node != nullptr && node->is_end;
    }
    
    bool startsWith(string prefix) {
        return searchPrefix(prefix) != nullptr;
    }
};

/**
 * Your Trie object will be instantiated and called as such:
 * Trie* obj = new Trie();
 * obj->insert(word);
 * bool param_2 = obj->search(word);
 * bool param_3 = obj->startsWith(prefix);
 */