Implementing the Sudoku Solver

To implement the Sudoku solver algorithm, we will use a backtracking approach. The goal is to fill in the empty cells of the Sudoku grid with numbers from 1 to 9, following the Sudoku rules.

Here are the steps to implement the Sudoku solver algorithm:

1. Create a function isValid to check if a number can be placed in a specific cell without violating the Sudoku rules. The function should check if the number already exists in the same row, the same column, or the same 3x3 box.

   TEXT/X-C++SRC

   1bool isValid(vector<vector<int>>& board, int row, int col, int num) {
   2    // Check if the number already exists in the row
   3    // Check if the number already exists in the column
   4    // Check if the number already exists in the 3x3 box
   5    return true;
   6}

2. Create a recursive function solveSudoku to solve the Sudoku puzzle. The function should iterate through each cell of the Sudoku grid and try different numbers until a valid solution is found. If a number violates the Sudoku rules, backtracking should be performed.

   TEXT/X-C++SRC

   1bool solveSudoku(vector<vector<int>>& board) {
   2    // Iterate through each cell of the Sudoku grid
   3    // If the cell is empty, try different numbers and recursively call `solveSudoku`
   4    // Perform backtracking if a number violates the Sudoku rules
   5    return true;
   6}

3. In the main function, create a sample Sudoku puzzle as a 2D vector with empty cells represented by 0.

   TEXT/X-C++SRC

   1vector<vector<int>> board = {
   2    {5, 3, 0, 0, 7, 0, 0, 0, 0},
   3    {6, 0, 0, 1, 9, 5, 0, 0, 0},
   4    {0, 9, 8, 0, 0, 0, 0, 6, 0},
   5    {8, 0, 0, 0, 6, 0, 0, 0, 3},
   6    {4, 0, 0, 8, 0, 3, 0, 0, 1},
   7    {7, 0, 0, 0, 2, 0, 0, 0, 6},
   8    {0, 6, 0, 0, 0, 0, 2, 8, 0},
   9    {0, 0, 0, 4, 1, 9, 0, 0, 5},
   10    {0, 0, 0, 0, 8, 0, 0, 7, 9}
   11};

4. Call the solveSudoku function with the Sudoku board vector as the argument.

   TEXT/X-C++SRC

   1if (solveSudoku(board)) {
   2    // Print the solved Sudoku board
   3} else {
   4    // Print an error message
   5}

By following these steps, we can implement the Sudoku solver algorithm in C++, which will fill in the empty cells of the Sudoku puzzle and find a valid solution. Feel free to customize the sample Sudoku puzzle to test the algorithm with different scenarios.

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}

#include <iostream>

#include <vector>

using namespace std;

​

bool isValid(vector<vector<int>>& board, int row, int col, int num) {

    // Check if the number already exists in the row

    for (int i = 0; i < 9; i++) {

        if (board[row][i] == num) {

            return false;

        }

    }

​

    // Check if the number already exists in the column

    for (int i = 0; i < 9; i++) {

        if (board[i][col] == num) {

            return false;

        }

    }

​

    // Check if the number already exists in the 3x3 box

    int startRow = (row / 3) * 3;

    int startCol = (col / 3) * 3;

    for (int i = 0; i < 3; i++) {

        for (int j = 0; j < 3; j++) {

            if (board[startRow + i][startCol + j] == num) {

                return false;

            }

        }

    }