vector<string> findWords(vector<vector<char> >& board, vector<string>& words) {
vector<string> ans;
if (board.empty() || board[0].empty() || words.empty())
return ans;
TrieNode* root = buildTrieTree(words);
for (int i=0; i<board.size(); i++) {
for (int j=0; j<board[0].size(); j++) {
if (root->getNext(board[i][j]) != NULL) {
dfs(ans, board, i, j, root->getNext(board[i][j]), "");
}
}
}
destroyTrieTree(root);
return ans;
}
TrieNode* buildTrieTree(vector<string>& words) {
TrieNode* root = new TrieNode();
for (string word : words) {
int index = 0;
TrieNode* cur = root;
while (index < word.size() && cur->getNext(word[index]) != NULL) {
cur = cur->getNext(word[index]);
index++;
}
while (index < word.size()) {
cur->setNext(word[index]);
cur = cur->getNext(word[index]);
index++;
}
cur->setIsWord(true);
}
return root;
}