class Solution
{
    public boolean isValidSudoku(char[][] board)
    {
        HashSet<Character> myHashSet = new HashSet<>();
        int count = 0;
        //rows
        for (int i = 0; i < 9; i++)
        {
            for (int j = 0; j < 9; j++)
            {
                if (board[i][j] != '.')
                {
                    myHashSet.add(board[i][j]);
                    count++;
                }
            }
            if(myHashSet.size()!=count)
                return false;
            myHashSet.clear();
            count = 0;
        }
        //columns
        for (int i = 0; i < 9; i++)
        {
            for (int j = 0; j < 9; j++)
            {
                if (board[j][i] != '.')
                {
                    myHashSet.add(board[j][i]);
                    count++;
                }
            }
            if(myHashSet.size()!=count)
                return false;
            myHashSet.clear();
            count = 0;
        }
        //3x3
        for (int i = 0; i < 9; i += 3)
            for (int j = 0; j < 9; j += 3)
            {
                for (int m = i; m < i + 2; m++)
                {
                    for (int n = j; n < j + 2; n++)
                    {
                        if(board[j][i] != '.')
                        {
                            myHashSet.add(board[j][i]);
                            count++;
                        }

                    }
                }
                if(myHashSet.size()!=count)
                    return false;
                myHashSet.clear();
                count = 0;
            }
        return true;
    }
}