Sudoku_Solver_CPP

#include <iostream>
using namespace std;

const int N = 9;

void printSudoku(int sudoku[N][N]) {
    for (int i = 0; i < N; i++) {
        for (int j = 0; j < N; j++) {
            cout << sudoku[i][j] << " ";
        }
        cout << endl;
    }
}

bool isSafe(int sudoku[N][N], int row, int col, int num) {
    for (int x = 0; x < N; x++) {
        if (sudoku[row][x] == num || sudoku[x][col] == num) {
            return false;
        }
    }

    int startRow = row - row % 3, startCol = col - col % 3;
    for (int i = 0; i < 3; i++) {
        for (int j = 0; j < 3; j++) {
            if (sudoku[i + startRow][j + startCol] == num) {
                return false;
            }
        }
    }

    return true;
}

bool solveSudoku(int sudoku[N][N]) {
    for (int row = 0; row < N; row++) {
        for (int col = 0; col < N; col++) {
            if (sudoku[row][col] == 0) {
                for (int num = 1; num <= N; num++) {
                    if (isSafe(sudoku, row, col, num)) {
                        sudoku[row][col] = num;
                        if (solveSudoku(sudoku)) {
                            return true;
                        }
                        sudoku[row][col] = 0;
                    }
                }
                return false;
            }
        }
    }
    return true;
}

int main() {
    int sudoku[N][N] = {
        {3, 0, 6, 5, 0, 8, 4, 0, 0},
        {5, 2, 0, 0, 0, 0, 0, 0, 0},
        {0, 8, 7, 0, 0, 0, 0, 3, 1},
        {0, 0, 3, 0, 1, 0, 0, 8, 0},
        {9, 0, 0, 8, 6, 3, 0, 0, 5},
        {0, 5, 0, 0, 9, 0, 6, 0, 0},
        {1, 3, 0, 0, 0, 0, 2, 5, 0},
        {0, 0, 0, 0, 0, 0, 0, 7, 4},
        {0, 0, 5, 2, 0, 6, 3, 0, 0}
    };

    if (solveSudoku(sudoku)) {
        cout << "Solved Sudoku:" << endl;
        printSudoku(sudoku);
    } else {
        cout << "Error: No solution exists for the given Sudoku puzzle." << endl;
    }

    return 0;
}