Sudoku Solver.cpp

class Solution {
public:
    
    bool issafe(vector<vector<char>> &board,int row,int col,char c)
    {
        for(int i=0;i<9;i++)
        {
            if(board[row][i]==c)
                return 0;
            if(board[i][col]==c)
                return 0;
            if(board[3*(row/3)+i/3][3*(col/3)+i%3]==c)
                return 0;
        }
        return 1;
    }
    
    bool solve(vector<vector<char>> & board)
    {
        for(int i=0;i<9;i++)
        {
            for(int j=0;j<9;j++)
            {
                if(board[i][j]=='.')
                {
                    for(char c='1';c<='9';c++)
                    {
                        if(issafe(board,i,j,c))
                        {
                            board[i][j]=c;
                            if(solve(board)==1)
                                return 1;
                            else
                                board[i][j]='.';
                        }
                    }
                    return 0;   
                }
            }
        }
        return 1;
    }
    
    void solveSudoku(vector<vector<char>>& board) {
        solve(board);
    }
};