Valid Sudoku

Determine if a Sudoku is valid, according to:
Sudoku Puzzles - The Rules.

The Sudoku board could be partially filled, where empty cells are filled with the character

'.'

.



A partially filled sudoku which is valid.
Note:

A valid Sudoku board (partially filled) is not necessarily solvable. Only the filled cells need to be validated.

Solution:

class Solution {
public:
bool isValidSudoku(vector<vector<char>>& board) {
vector<vector<bool> > row(9, vector<bool>(10, true));
vector<vector<bool> > col(9, vector<bool>(10, true));
vector<vector<bool> > small(9, vector<bool>(10, true));
for(int i = 0; i < 9; ++i)
for(int j = 0; j < 9; ++j)
{
if(board[i][j] == '.') continue;
int val = board[i][j] - '0';
if(row[i][val]) row[i][val] = false;
else return false;
if(col[j][val]) col[j][val] = false;
else return false;
if(small[(i/3)*3+j/3][val]) small[(i/3)*3+j/3][val] = false;
else return false;
}

return true;
}
};