LeetCode – Refresh – Valid Sudoku

Everytime forget to - '0'!!!!!!!

class Solution {
public:
    bool isValid(vector<bool> &rec, int value) {
        if (value < 0) return true;
        if (rec[value]) return false;
        rec[value] = true;
        return true;
    }
    bool isValidSudoku(vector<vector<char> > &board) {
        if (board.size() != 9 || board[0].size() != 9) return false;
        for (int i = 0; i < 9; i++) {
            vector<bool> row(10, false), column(10, false), sub(10, false);
            for (int j = 0; j < 9; j++) {
                if (!isValid(row, board[i][j] - '0') ||
                    !isValid(column, board[j][i] - '0') ||
                    !isValid(sub, board[(i/3)*3 + j/3][(i%3)*3 + j%3] - '0')) {
                        return false;
                }
            }
        }
        return true;
    }
};