【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.

Note:
A valid Sudoku board (partially filled) is not necessarily solvable. Only the filled cells need to be validated.

 

数独的规则：

 

在一个9*9的区域内，

每行1-9出现且只出现一次，

每列1-9出现且只出现一次，

在9个子3*3的区域内1-9出现且只出现一次。

 这题允许填空('.')，所以不必要每个数字都出现。

 

 1 class Solution {

 2 public:

 3     bool isValidSudoku(vector<vector<char> > &board) {

 4         

 5         return  isValidRow(board)&&isValidColumn(board)&&isValidBox(board);

 6     }

 7     

 8     

 9     bool isValidRow(vector<vector<char> > &board)

10     {

11         map<int,bool> hash;

12         for(int i=0;i<9;i++)

13         {

14             for(int j=0;j<9;j++)

15             {

16                 if(board[i][j]=='.') continue;

17                 if(hash.find(board[i][j])!=hash.end()) return false;

18                 hash[board[i][j]]=true;

19                 

20             }

21             hash.clear();

22         }

23         return true;

24     }

25     

26     bool isValidColumn(vector<vector<char> > &board)

27     {

28         map<int,bool> hash;

29         for(int i=0;i<9;i++)

30         {

31             for(int j=0;j<9;j++)

32             {

33                 if(board[j][i]=='.') continue;

34                 if(hash.find(board[j][i])!=hash.end()) return false;

35                 hash[board[j][i]]=true;

36                 

37             }

38             hash.clear();

39         }

40         return true;

41     }

42     

43     bool isValidBox(vector<vector<char> > &board)

44     {

45         int p[9][2]={{0,0},{0,3},{0,6},{3,0},{3,3},{3,6},{6,0},{6,3},{6,6}};

46         map<int,bool> hash;

47         for(int h=0;h<9;h++)

48         {

49             for(int i=0+p[h][0];i<3+p[h][0];i++)

50             {

51                 for(int j=0+p[h][1];j<3+p[h][1];j++)

52                 {

53                     if(board[i][j]=='.') continue;

54                     if(hash.find(board[i][j])!=hash.end()) return false;

55                     hash[board[i][j]]=true;

56                 }

57             }

58             hash.clear();

59         }

60         return true;

61     }

62 };