题目描述:()

Determine if a Sudoku is valid, according to: .

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.

解题思路：

先验证行，再验证列，最后验证小方格！

1 class Solution { 2 public: 3     bool isValidSudoku(vector
     
      
       >& board) { 4         bool used[9]; 5          6         for (int i = 0; i < 9; ++i) { 7             memset(used, false, sizeof(used)); 8             for (int j = 0; j < 9; ++j) { 9                 if (!isVaild(board[i][j], used)) {10                     return false;11                 }12             }13             14             memset(used, false, sizeof(used));15             for (int j = 0; j < 9; ++j) {16                 if (!isVaild(board[j][i], used)) {17                     return false;18                 }19             }20         }21         22         for (int r = 0; r < 3; ++r) {23             for (int c = 0; c < 3; ++c) {24                 memset(used, false, sizeof(used));25                 26                 for (int i = r * 3; i < 3 * r + 3; ++i) {27                     for (int j = c * 3; j < 3 * c + 3; ++j) {28                         if (!isVaild(board[i][j], used)) {29                             return false;30                         }31                     }32                 }33             }34         }35         36         return true;37     }38 private:39     bool isVaild(char c, bool *used) {40         if (c == '.') {41             return true;42         }43         44         if (used[c - '1']) {45             return false;46         }47         48         used[c - '1'] = true;49         return true;50     }51 };