Sudoku_Solver.cpp

#include<iostream>
#include<vector>
using namespace std;

bool isSafe(int row, int col,vector<vector<int>> &board, int val)
{
    for(int i=0; i<board.size(); i++)
    {
        if(board[row][i]==val)
            return false;
        
        if(board[i][col]==val)
            return false;
        
        if(board[3*(row/3)+i/3][3*(col/3) + i%3]==val)
            return false;
    }

    return true;
}

bool solve(vector<vector<int>> &board)
{
    int n = board.size();

    for(int i=0; i<n; i++)
    {
        for(int j=0; i<n; j++)
        {
            if(board[i][j]==0)          // block is empty
            {
                for(int val=1; val<=9; val++)
                {
                    if(isSafe(i,j,board,val))
                    {
                        board[i][j] = val;

                        bool possible = solve(board);
                        if(possible)
                            return true;
                        else
                            board[i][j] = 0;
                    }
                }

                return false;
            }
        }
    }

    return true;
}

int main()
{
    
    return 0;
}