LeetCode Valid Sudoku

题目：

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.

class Solution {
public:
	bool isValidSudoku(vector<vector<char> > &board) {
		return isValidRow(board) && isValidCol(board) && isValidSub(board);
	}
private:
	bool isValidRow(vector<vector<char>> &a) {
		for (int i = 0; i < 9; i++) {
			int tmp[255] = { 0 };
			for (int j = 0; j < 9; j++)
				tmp[a[i][j]]++;
			for (int k = '0'; k <= '9'; k++) {
				if (tmp[k] >1)
					return false;
			}
		}
		return true;
	}
	bool isValidCol(vector<vector<char>> &a) {
		for (int j = 0; j < 9; j++) {
			int tmp[255] = { 0 };
			for (int i = 0; i < 9; i++)
				tmp[a[i][j]]++;
			for (int k = '0'; k <= '9'; k++) {
				if (tmp[k] > 1)
					return false;
			}
		}
		return true;
	}
	bool isValidSub(vector<vector<char>> &a) {
		for (int i = 0; i < 9; i += 3) {
			for (int j = 0; j < 7; j += 3) {
				int tmp[255] = { 0 };
				for (int m = 0; m < 3; m++) {
					for (int n = 0; n < 3; n++)
						tmp[a[i + m][j + n]]++;
				}
				for (int k = '0'; k <= '9'; k++) {
					if (tmp[k] > 1)
						return false;
				}
			}
		}
		return true;
	}
};