Valid Sudoku (Easy)

Description

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 ‘.’.

Analysis

判断一个数独是否是合法的。直接hash行，列以及每个九宫格判断是否重复即可

My Solution

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//C++
class Solution {
public:
    bool isValidSudoku(vector<vector<char> > &board) {
        int row[9][9],col[9][9],sq[9][9];
        memset(row,0,sizeof(row));
        memset(col,0,sizeof(col));
        memset(sq,0,sizeof(sq));
        for(int i = (int)board.size()-1; i>=0 ; i--)
        {
            for(int j = board[i].size()-1; j>=0 ; j--)
            {
                if(!(board[i][j]>='1'&&board[i][j]<='9'))
                    continue;
                int x = board[i][j]-'1';
                int y = i/3*3+j/3;
                if(row[i][x]||col[j][x]||sq[y][x])
                    return false;
                row[i][x]=col[j][x]=sq[y][x]=1;
            }
        }
        return true;
    }
};