TrieNode *searchPattern(string word) {
    typedef std::pair<TrieNode *, int> Match;
    stack<Match>s;
    s.push(make_pair(root, 0));
    int len = word.length();
    while (!s.empty()) {
      Match m = s.top();
      TrieNode *node = m.first;
      s.pop();

      int id = m.second;
      if (id >= len) {
        if (node->isEnd() || s.empty()) {
          return node;
        }
        continue;
      }

      char ch = word[m.second];
      if (ch == '.') {
        for (int i = 0; i < TrieNode::R; i++) {
          if (node->links[i]) {
            s.push(make_pair(node->links[i], id + 1));
          }
        }
      } else if (node->containsKey(ch)) {
        s.push(make_pair(node->get(ch), id + 1));
      }
    }
    return NULL;
  }
 // Returns if the word is in the trie.
 bool search(string word) {
   //TrieNode *node = searchPrefix(word);
   TrieNode *node = searchPattern(word);
   return node != NULL && node->isEnd();
 }