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class TrieNode {
public:
    bool end;
    TrieNode* children[26];
    TrieNode() {
        end = false;
        for(int i=0; i<26; i++)
            children[i] = NULL;
    }
};

class WordDictionary {
public:
    /** Initialize your data structure here. */
    WordDictionary() {

    }

    /** Adds a word into the data structure. */
    void addWord(string word) {
        TrieNode* node = root;
        for(char c : word) {
            c -= 'a';
            if(!node->children[c]) {
                node->children[c] = new TrieNode();
            }
            node = node->children[c];
        }
        node->end = true;
    }

    /** Returns if the word is in the data structure. A word could contain the dot character '.' to represent any one letter. */
    bool search(string word) {
        return search(word.c_str(), root);
    }

private:
    TrieNode* root = new TrieNode();

    bool search(const char* word, TrieNode* node) {
        for(int i = 0; word[i] && node; i++) {
            if(word[i] != '.') {
                node = node->children[word[i] - 'a'];
            } else {
                TrieNode* tmp = node;
                for(int j = 0; j < 26; j++) {
                    node = tmp->children[j];
                    if(search(word + i + 1, node)) {
                        return true;
                    }
                }
            }
        }
        return node && node->end;
    }
};