bool exist(vector<vector<char>>& board, string word)
{
if(board.empty() || board[0].empty())
{
return false;
}
int row = board.size();
int col = board[0].size();
typedef std::unordered_map<char, std::vector<std::pair<int,int>>> CharMap;
CharMap charMap;
for(int i = 0; i < board.size(); ++i)
{
for(int j = 0; j < board[i].size(); ++j)
{
char c = board[i][j];
if(charMap.find(c) == charMap.end())
{
charMap[c] = std::vector<std::pair<int,int>>{std::make_pair(i, j)};
}
else
{
charMap[c].push_back(std::make_pair(i, j));
}
}
}
vector<vector<bool>> visited(row, vector<bool>(col, false));
if(charMap.find(word[0]) != charMap.end())
{
for(const auto& p : charMap[word[0]])
{
visited[p.first][p.second] = true;
if(impl(board, row, col, visited, word, 1, p.first, p.second))
{
return true;
}
visited[p.first][p.second] = false;
}
}
return false;
}
void removeDuplicates(Node* head) {
CharMap map;
Node* n = head;
do {
map[n->val]++;
n = n->next;
} while(n);
for(CharMap::const_iterator it = map.begin(); it != map.end(); ++it) {
int cnt = it->second;
while(cnt > 1) {
head = removeNode(head, it->first);
--cnt;
}
}
}