sudoku board

function isValid(board, row, col, num) {
  // Check row and column
  for (let i = 0; i < 9; i++) {
    if (board[row][i] === num || board[i][col] === num) {
      return false;
    }
  }

  // Check 3x3 box
  const startRow = Math.floor(row / 3) * 3;
  const startCol = Math.floor(col / 3) * 3;
  for (let i = 0; i < 3; i++) {
    for (let j = 0; j < 3; j++) {
      if (board[startRow + i][startCol + j] === num) {
        return false;
      }
    }
  }

  return true;
}

function shuffle(array) {
  for (let i = array.length - 1; i > 0; i--) {
    const j = Math.floor(Math.random() * (i + 1));
    [array[i], array[j]] = [array[j], array[i]];
  }
  return array;
}

function solveSudoku(board) {
  for (let row = 0; row < 9; row++) {
    for (let col = 0; col < 9; col++) {
      if (board[row][col] === 0) {
        const numbers = shuffle([...Array(9).keys()].map(i => i + 1));
        for (const num of numbers) {
          if (isValid(board, row, col, num)) {
            board[row][col] = num;
            if (solveSudoku(board)) return true;
            board[row][col] = 0;
          }
        }
        return false; // No valid number found
      }
    }
  }
  return true; // Solved
}

function generateSudoku() {
  const board = Array.from({ length: 9 }, () => Array(9).fill(0));
  solveSudoku(board);
  return board;
}

// Generate and display the Sudoku grid
const sudoku = generateSudoku();
sudoku.forEach(row => console.log(row.join(' ')));