Question

how to write sudoku game solution using OOPs in c++

Answer 1

#include <iostream>
using namespace std;

class Sudoku {
private:
    static const int SIZE = 9;
    int board[SIZE][SIZE];

public:
    // Constructor
    Sudoku(int initialBoard[SIZE][SIZE]) {
        for (int i = 0; i < SIZE; i++)
            for (int j = 0; j < SIZE; j++)
                board[i][j] = initialBoard[i][j];
    }

    // Print the Sudoku board
    void printBoard() {
        for (int i = 0; i < SIZE; i++) {
            for (int j = 0; j < SIZE; j++) {
                cout << board[i][j] << " ";
            }
            cout << endl;
        }
    }

    // Check if num can be placed at board[row][col]
    bool isSafe(int row, int col, int num) {
        // Check row & column
        for (int x = 0; x < SIZE; x++) {
            if (board[row][x] == num || board[x][col] == num)
                return false;
        }

        // Check 3x3 sub-grid
        int startRow = row - row % 3;
        int startCol = col - col % 3;

        for (int i = 0; i < 3; i++)
            for (int j = 0; j < 3; j++)
                if (board[startRow + i][startCol + j] == num)
                    return false;

        return true;
    }

    // Find empty cell
    bool findEmptyCell(int &row, int &col) {
        for (row = 0; row < SIZE; row++)
            for (col = 0; col < SIZE; col++)
                if (board[row][col] == 0)
                    return true;
        return false;
    }

    // Solve Sudoku using Backtracking
    bool solve() {
        int row, col;

        if (!findEmptyCell(row, col))
            return true;  // Solved

        for (int num = 1; num <= 9; num++) {
            if (isSafe(row, col, num)) {
                board[row][col] = num;

                if (solve())
                    return true;

                board[row][col] = 0; // Backtrack
            }
        }
        return false;
    }
};