请你判断一个 9 x 9 的数独是否有效。只需要 根据以下规则 ，验证已经填入的数字是否有效即可。
数字 1-9 在每一行只能出现一次。
数字 1-9 在每一列只能出现一次。
数字 1-9 在每一个以粗实线分隔的 3x3 宫内只能出现一次。（请参考示例图）
注意：
一个有效的数独（部分已被填充）不一定是可解的。
只需要根据以上规则，验证已经填入的数字是否有效即可。
空白格用 '.' 表示。
示例 1：
输入：board =
[["5","3",".",".","7",".",".",".","."]
,["6",".",".","1","9","5",".",".","."]
,[".","9","8",".",".",".",".","6","."]
,["8",".",".",".","6",".",".",".","3"]
,["4",".",".","8",".","3",".",".","1"]
,["7",".",".",".","2",".",".",".","6"]
,[".","6",".",".",".",".","2","8","."]
,[".",".",".","4","1","9",".",".","5"]
,[".",".",".",".","8",".",".","7","9"]]
输出：true
代码
class Solution {
public:
bool isValidSudoku(vector<vector<char>>& board) {
int row[9][10] = {0};
int col[9][10] = {0};
int box[9][10] = {0};
for(int i = 0;i < 9;i++){
for(int j = 0;j < 9;j++){
if(board[i][j] == '.') continue;
int cur_char = board[i][j] - '0';
if(row[i][cur_char]) return false;
if(col[j][cur_char]) return false;
if(box[j/3 + (i/3)*3][cur_char]) return false;
row[i][cur_char] = 1;
col[j][cur_char] = 1;
box[j/3 + (i/3)*3][cur_char] = 1;
}
}
return true;
}
};