LeetCode Valid Sudoku

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.

class Solution {
public:
    bool isValidSudoku(vector<vector<char> > &board) {
        set<int> nums;
		for(int i = 0; i < 9; ++i)
		{
			nums.clear();
			for(int j = 0; j < 9; ++j)
			{
				if('.' != board[i][j])
				{
					if(nums.count(board[i][j]) > 0)
						return false;
					else
						nums.insert(board[i][j]);
				}
			}
		}

		for(int i = 0; i < 9; ++i)
		{
			nums.clear();
			for(int j = 0; j < 9; ++j)
			{
				if('.' != board[j][i])
				{
					if(nums.count(board[j][i]) > 0)
						return false;
					else
						nums.insert(board[j][i]);
				}
			}
		}

		for(int i = 0; i < 3; ++i)
		{
			for(int j = 0; j < 3; ++j)
			{
				nums.clear();
				for(int x = 0; x < 3; ++x)
				{
					for(int y = 0; y < 3; ++y)
					{
						if('.' != board[i*3+x][j*3+y])
						{
							if(nums.count(board[i*3+x][j*3+y]) > 0)
								return false;
							else
								nums.insert(board[i*3+x][j*3+y]);
						}
					}
				}
			}
		}
		return true;
    }
};