php生成数独和判断数独是否是合理的数独，并给出解决方案：

<?phpnamespace numbers;require "SudokuGenerator.php";class SudokuSolve
{/*** 解数独* @param String[][] $board* @return NULL*/public function solveSudoku(&$board){if (count($board) != 9 || count($board[0]) != 9) return false;//初始化$rows = $columns = $blocks = [];$nums = array_flip(range(1, 9));for ($i = 0; $i < 9; $i++) {$rows[$i] = $nums;$columns[$i] = $nums;$blocks[$i] = $nums;}//收集需要填数的位置$empty = [];for ($i = 0; $i < 9; $i++) {for ($j = 0; $j < 9; $j++) {if ($board[$i][$j] != '.') {$num = $board[$i][$j];$b = intval($i / 3) * 3 + intval($j / 3);unset($rows[$i][$num], $columns[$j][$num], $blocks[$b][$num]);} else {$empty[] = [$i, $j];}}}return $this->backtrack($board, $empty, $rows, $columns, $blocks);}private function backtrack(&$board, $empty, $rows, $columns, $blocks, $index = 0){if ($index == count($empty)) {return true;}[$i, $j] = $empty[$index];$b = intval($i / 3) * 3 + intval($j / 3);$nums = array_intersect(array_keys($rows[$i]), array_keys($columns[$j]), array_keys($blocks[$b]));foreach ($nums as $num) {unset($rows[$i][$num], $columns[$j][$num], $blocks[$b][$num]);$board[$i][$j] = (int)$num;if ($this->backtrack($board, $empty, $rows, $columns, $blocks, $index + 1))return true;$rows[$i][$num] = $num;$columns[$j][$num] = $num;$blocks[$b][$num] = $num;}return false;}// 对前端传来的数独结果进行检测public function isValidSudoku($board){$rows = array_fill(0, 9, array_fill(0, 9, false));$columns = array_fill(0, 9, array_fill(0, 9, false));$subBoxes = array_fill(0, 3, array_fill(0, 3, array_fill(0, 9, false)));foreach ($board as $i => $row) {foreach ($row as $j => $c) {if ($c !== 0) {$index = ord($c) - ord('1');if ($rows[$i][$index] || $columns[$j][$index] || $subBoxes[$i / 3][$j / 3][$index]) {return false;}$rows[$i][$index] = true;$columns[$j][$index] = true;$subBoxes[$i / 3][$j / 3][$index] = true;}}}return true;}
}$solution = new SudokuSolve();
$board =// [["5", "3", 0, 0, "7", 0, 0, 0, 0], ["6", 0, 0, "1", "9", "5", 0, 0, 0], [0, "9", "8", 0, 0, 0, 0, "6", 0], ["8", 0, 0, 0, "6", 0, 0, 0, "3"], ["4", 0, 0, "8", 0, "3", 0, 0, "1"], ["7", 0, 0, 0, "2", 0, 0, 0, "6"], [0, "6", 0, 0, 0, 0, "2", "8", 0], [0, 0, 0, "4", "1", "9", 0, 0, "5"], [0, 0, 0, 0, "8", 0, 0, "7", "9"]];
// $board = [[4, 7, 0, 3, 9, 1, 5, 6, 2], [0, 0, 0, 0, 5, 6, 4, 1, 7], [6, 1, 0, 4, 7, 2, 9, 8, 3], [0, 0, 6, 2, 0, 3, 1, 7, 0], [8, 2, 1, 7, 6, 0, 0, 9, 4], [3, 5, 7, 1, 4, 9, 0, 2, 0], [1, 9, 4, 5, 2, 0, 6, 3, 8], [7, 8, 0, 6, 1, 4, 2, 0, 9], [0, 6, 2, 9, 0, 0, 0, 4, 1]];
$sudokuGenerator = new SudokuGenerator();
$sudoku = $sudokuGenerator->generateSudoku();
$board = $sudokuGenerator->removeNumbers(60);  // 难度级别，可以调整，越大越难
var_dump(json_encode($board, 320));$isValidSudoku = $solution->isValidSudoku($board);
if (!$isValidSudoku) {echo '数独不合法！';die();
}
echo '数独合法！解答如下：';
$solution->solveSudoku($board);// 数独结果
var_dump(json_encode($board, 320));