Class Solution

Backtracking/Homework/sudokuSolver.cpp:13–72

} Driver Code Ends

 // } Driver Code Ends
class Solution 
{
    public:
    //Function to find a solved Sudoku. 
    bool check(int grid[N][N],int row, int col, int num){
        //row
        for(int i=0;i<9;i++){
            if(grid[i][col]==num) return false;
        }
        //col
        for(int j=0;j<9;j++){
            if(grid[row][j]==num) return false;
        }        
        //box
        int ini =row-row%3;
        int inj=col-col%3;
        
        for(int i=0;i<3;i++){
            for(int j=0;j<3;j++){
                if(grid[ini+i][inj+j]==num) return false;
            }
        }
        
        return true;
    }
    bool helper(int grid[N][N], int row ,int col){
        if (row==9) return true;
        if (col==9) return helper(grid,row+1,0);
        if (grid[row][col] != 0) return helper(grid,row,col+1);
        
        for(int i=1;i<=9;i++){
            if (check(grid,row,col,i)){
                grid[row][col]=i;
                if (helper(grid,row,col+1)){
                    return true;
                }
            }
            grid[row][col]=0;
        }
        return false;
        
    }
    bool SolveSudoku(int grid[N][N])  
    { 
        // Your code here
        return helper(grid,0,0);
    }
    
    //Function to print grids of the Sudoku.
    void printGrid (int grid[N][N]) 
    {
        // Your code here 
        
        for(int i=0;i<9;i++){
            for(int j=0;j<9;j++){
                cout<<grid[i][j]<<" ";
            }
        }