Local Hack Day 3

` class Solution { public: //varification functio- character c can put on board[row][col] or not bool isValid(vector>& board, int row, int col, char c) { for(int i = 0; i < 9; i++) { if(board[i][col] == c) //Each of the digits 1-9 must occur exactly once in each row. return false;

        if(board[row][i] == c) //Each of the digits 1-9 must occur exactly once in each column.
            return false; 

        if(board[3 * (row / 3) + i / 3][3 * (col / 3) + i % 3] == c) //Each of the digits 1-9 must occur exactly once in each of the 9 3x3 sub-boxes of the grid.
            return false; 
    }
    return true;
}    

bool solve(vector<vector<char>>& board)
{
    for(int i = 0; i < board.size(); i++)
    {
        for(int j = 0; j < board[0].size(); j++)
        {
            if(board[i][j] == '.')
            {
                for(char c = '1'; c <= '9'; c++)
                {
                    if(isValid(board, i, j, c)) //checking c digit can put that position or not
                    {
                        board[i][j] = c; 

                        if(solve(board))  //if borad is fully solved return true                        
                            return true; 
                        else
                            board[i][j] = '.'; 
                    }
                } 
                return false;
            }
        }
    }
    return true;
}

void solveSudoku(vector<vector<char>>& board) 
{
    solve(board);
}

}; `

Built With

• c++