#include <iostream>
#include <fstream>
#include <string>
#include <conio.h>
#include <vector>
using namespace std;

struct Grid 
{ 
   vector<vector<int> > gameboard; // Holds puzzle.
};

class Sudoku
{
	public:
		
		// Precondition: input file exists or input numbers are valid.
		// Postcondition: an array of 81 integers is created - the Sudoku board.
		void createGrid(Grid &gameboard);

		// Precondition: createGrid(...) has been called.
		// Postcondition: Solution to puzzle is displayed if possible - exits if not possible.
		int Solve(int loc, int loc2, int num, Grid &gameboard);

	private:
		// Precondition: A valid location is passed.
		// Postcondition: Moves to next empty space.
		void place_next(int &loc, int &loc2, Grid *pboard);

		// Counts number of correct entries to verify when puzzle complete.
		int counter;

		// Precondition: A valid location and attempted value are input.
		// Postcondition: Returns whether or not this value already exists in same row.
		bool row_check(int loc, int val, Grid *pboard);

		// Precondition: A valid location and attempted value are input.
		// Postcondition: Returns whether or not this value already exists in same column.
		bool column_check(int loc2, int val, Grid *pboard);

		// Precondition: A valid location and attempted value are input.
		// Postcondition: Returns whether or not this value already exists in same location in other square.
		bool square_check(int loc, int loc2, int val, Grid *pboard);

		// Precondition: Puzzle is solveable.
		// Postcondition: Prints out solution.
		void print_solution(Grid *pboard);
};