[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.

 

class Solution
{
public:
  bool isValidSudoku(vector<vector<char> > &board)
  {
    int i = 0, j = 0;
    map<char, int> count;
    
    //判断行是否合法
    for(i = 0; i < 9; i++)
    {
      count.clear();
      for(j = 0; j < 9; j++)
      {
        count[board[i][j]]++;
        if(count[board[i][j]] > 1 && board[i][j] != '.')
          return false;
      }
    }

    //判断列是否合法
    for(i = 0; i < 9; i++)
    {
      count.clear();
      for(j = 0; j < 9; j++)
      {
        count[board[j][i]]++;
        if(count[board[j][i]] > 1 && board[j][i] != '.')
          return false;
      }
    }

    // 判断九个小方块是否合法
    for(i = 0; i < 9; i = i+3)
    {
      for(j = 0; j < 9; j = j+3)
      {
        count.clear();
        for(int m = 0; m < 3; m++)
        {
          for(int n = 0; n < 3; n++)
          {
            count[board[i + m][j + n]]++;
            if(count[board[i + m][j + n]] > 1 && board[i + m][j + n] != '.')
              return false;
          }
        }
      }
    }

    return true;
  }
};