Solve N-Queens Problem in PHP with Backtracking

<?php

function printBoard($board) {
    foreach ($board as $row) {
        echo implode(' ', $row) . "\\n";
    }
    echo "\\n";
}

function isSafe($board, $row, $col) {
    // ها چک کردن سطرها و ستون‌
    for ($i = 0; $i < $col; $i++) {
        if ($board[$row][$i] == 'Q') {
            return false;
        }
    }

// چک کردن قطر اصلی
    for ($i = $row, $j = $col; $i >= 0 && $j >= 0; $i--, $j--) {
        if ($board[$i][$j] == 'Q') {
            return false;
        }
    }

// چک کردن قطر فرعی
    for ($i = $row, $j = $col; $i < count($board) && $j >= 0; $i++, $j--) {
        if ($board[$i][$j] == 'Q') {
            return false;
        }
    }

return true;
}

function solveNQueensUtil(&$board, $col) {
    if ($col >= count($board)) {
        printBoard($board);
        return true;
    }

$res = false;
    for ($i = 0; $i < count($board); $i++) {
        if (isSafe($board, $i, $col)) {
            $board[$i][$col] = 'Q';
            $res = solveNQueensUtil($board, $col + 1) || $res;
            $board[$i][$col] = '.'; // Backtracking
        }
    }

return $res;
}

function solveNQueens($n) {
    $board = array_fill(0, $n, array_fill(0, $n, '.'));
    if (!solveNQueensUtil($board, 0)) {
        echo "No solution exists\\n";
    }
}

// اجرای برنامه
solveNQueens(8);

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Solve N-Queens Problem in PHP with Backtracking