void generateBoard(vector<int>& board, vector<vector<string>>& solutions, int n){
if(board.size() == n){
if(isValidCross(board)){
vector<string> solution;
for(int i=0; i<n; i++){
string line(n, '.');
line[board[i]] = 'Q';
solution.push_back(line);
}
solutions.push_back(solution);
}
return;
}
for(int i=0; i<n; i++){
bool exist = false;
for(int j=0; j<board.size(); j++){
if(board[j] == i){
exist = true;
break;
}
}
if(!exist){
board.push_back(i);
if(isValidCross(board)) generateBoard(board, solutions, n);
board.pop_back();
}
}
}
void visitCross(int x, int y){
Picture[x][y] = '*';
int i;
for (i = 0; i < 4; i++)
if (isValidCross(x + dx[i], y + dy[i]))
visitCross(x + dx[i], y + dy[i]);
}
