如何检查数独棋盘上的所有子网格，而不是只检查一个

function checkSudoku(board) {
  const size = 9;

  // 遍历每个子网格
  for (let row = 0; row < size; row += 3) {
    for (let col = 0; col < size; col += 3) {
      const seen = new Set();

      // 检查子网格中的数字是否唯一
      for (let i = 0; i < 3; i++) {
        for (let j = 0; j < 3; j++) {
          const num = board[row + i][col + j];

          // 检查数字是否已经存在
          if (seen.has(num)) {
            return false; // 数独棋盘无效
          }

          seen.add(num);
        }
      }
    }
  }

  return true; // 数独棋盘有效
}

// 示例数独棋盘
const sudokuBoard = [
  [5, 3, 4, 6, 7, 8, 9, 1, 2],
  [6, 7, 2, 1, 9, 5, 3, 4, 8],
  [1, 9, 8, 3, 4, 2, 5, 6, 7],
  [8, 5, 9, 7, 6, 1, 4, 2, 3],
  [4, 2, 6, 8, 5, 3, 7, 9, 1],
  [7, 1, 3, 9, 2, 4, 8, 5, 6],
  [9, 6, 1, 5, 3, 7, 2, 8, 4],
  [2, 8, 7, 4, 1, 9, 6, 3, 5],
  [3, 4, 5, 2, 8, 6, 1, 7, 9]
];

console.log(checkSudoku(sudokuBoard)); // 输出 true，数独棋盘有效