class Solution {
public:
    bool isValidSudoku(vector<vector<char>>& board) {
        int rows[9][9];
        int columns[9][9];
        int subboxes[3][3][9];
        
        memset(rows,0,sizeof(rows));
        memset(columns,0,sizeof(columns));
        memset(subboxes,0,sizeof(subboxes));
        for (int i = 0; i < 9; i++) 
        {
            for (int j = 0; j < 9; j++) 
            {
                char c = board[i][j];
                if (c != '.') 
                {
                    int index = c - '1';
                    rows[i][index]++;
                    columns[j][index]++;
                    subboxes[i / 3][j / 3][index]++;
                    if (rows[i][index] > 1 || columns[j][index] > 1 
                    || subboxes[i / 3][j / 3][index] > 1) 
                    {
                        return false;
                    }
                }
            }
        }
        return true;


    }
};