def solveNQueens(self, n):
        """
        :type n: int
        :rtype: List[List[str]]
        """
        # recusive
        if n == 0:
            return 0
        res = []
        board = [['.'] * n for t in range(n)]
        self.do_solveNQueens(res, board, n)
        return res

        :type n: int
        :rtype: List[List[str]]
        
python/051_N-Queens.py