【leetcode】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.

 

class Solution {
public:
    bool isValidSudoku(vector<vector<char>>& board) {
        bool used[9];

        for(int i=0;i<9;i++)
        {
            fill(used,used+9,false);
            for(int j=0;j<9;j++) //row
            {
                if(check(board[i][j],used)==false)
                    return false
            }

            fill(used,used+9,false);
            for(int j=0;j<9;j++) //col
            {
                if(check(board[j][i],used)==false)
                    return false;
            }
        }

        for(int r=0;r<3;r++)
        {
            for(int c=0;c<3;c++)
            {
                fill(used,used+9,false);
                for(int i=r*3;i<r*3+3;i++)
                {
                    for(int j=c*3;j<c*3+3;j++)
                        if(check(board[i][j],used)==false)
                            return false;
                }
            }
        }

        return true;
    }

    bool check(char ch,bool used[9])
    {
        if(ch=='.') return true;

        if(used[ch-'1']) return false;

        return used[ch-'1']=true;

    }
};