LeetCode之“散列表”：Valid Sudoku

　　题目链接

　　题目要求：

　　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.

　　这道题解法暂没有比较巧妙的，所以下边程序所用方法就是Brute Force（暴力破解）：

 class Solution {
 public:
     int charToInt(char c)
     {
         char str[] = {'', '', '', '', '', '', '', '', ''};
         int intStr[] = {, , , , , , , , };
         for(int i = ; i < ; i++)
         {
             if(c == str[i])
                 return intStr[i];
         }
         return -;
     }

     bool isValidSudoku(vector<vector<char>>& board) {
         unordered_map<int, int> hashMap;
         for(int i = ; i < ; i++)
             hashMap[i] = ;
         // row by row
         for(int i = ; i < ; i++)
         {
             for(int k = ; k < ; k++)
                 hashMap[k] = ;
             for(int j = ; j < ; j++)
             {
                 int tmp = charToInt(board[i][j]);
                 if(tmp != -)
                 {
                     hashMap[tmp]++;
                     if(hashMap[tmp] > )
                         return false;
                 }
             }
         }
         // column by column
         for(int j = ; j < ; j++)
         {
             for(int k = ; k < ; k++)
                 hashMap[k] = ;
             for(int i = ; i < ; i++)
             {
                 int tmp = charToInt(board[i][j]);
                 if(tmp != -)
                 {
                     hashMap[tmp]++;
                     if(hashMap[tmp] > )
                         return false;
                 }
             }
         }
         // 3*3 boxes by 3*3 boxes
         for(int i = ; i < ; i += )
         {
             for(int j = ; j < ; j += )
             {
                 for(int k = ; k < ; k++)
                     hashMap[k] = ;
                 for(int m = i; m < i + ; m++)
                     for(int n = j; n < j + ; n++)
                     {
                         int tmp = charToInt(board[m][n]);
                         if(tmp != -)
                         {
                             hashMap[tmp]++;
                             if(hashMap[tmp] > )
                                 return false;
                         }
                     }
             }
         }

         return true;
     }
 };