LeetCode 35. Valid Sudoku

数独规则：

考察每行、每列、以及九个九宫格中的任意一个（题中已用粗线分割），都不包含重复的数字（即至多只有一个1, 2, 3, ..., 9）

代码：

class Solution {public:    bool isValidSudoku(vector<vector<char> > &board)     {        vector<int> cnt(9, 0);        for (int i = 0; i < 9; ++ i)        {cnt.assign(9, 0);        for (int j = 0; j < 9; ++ j)        {        if (board[i][j] == '.')        {        continue;        } else if ( ++ cnt[board[i][j] - '1'] > 1)        {        return false;        }        }        }        for (int j = 0; j < 9; ++ j)        {        cnt.assign(9, 0);        for (int i = 0; i < 9; ++ i)        {        if (board[i][j] == '.')        {        continue;        } else if ( ++ cnt[board[i][j] - '1'] > 1)        {        return false;        }        }        }        return square_judge(0, 0, board) && square_judge(0, 3, board) && square_judge(0, 6, board)        && square_judge(3, 0, board) && square_judge(3, 3, board) && square_judge(3, 6, board)        && square_judge(6, 0, board) && square_judge(6, 3, board) && square_judge(6, 6, board);    }private:bool square_judge(int x, int y, const vector<vector<char> > &board){vector<int> cnt(9, 0);for (int i = 0; i < 3; ++ i){for (int j = 0; j < 3; ++ j){        if (board[x+i][y+j] == '.')        {        continue;        } else if ( ++ cnt[board[x+i][y+j] - '1'] > 1)        {        return false;        }}}return true;}};