* Stack.php

<?php
/**
 * Created by PhpStorm.
 * User: Mch
 * Date: 9/24/18
 * Time: 9:30 AM
 */

namespace ds\stack;

class Stack extends \SplStack {
    /**
     * 使用遞迴函式實現棧的逆序, 不使用其他資料結構
     */
    public function reverse() {
        if ($this->isEmpty()) {
            return;
        }
        $i = self::getAndRemoveLastElement($this);
        $this->reverse();
        $this->push($i);
    }

    private static function getAndRemoveLastElement(Stack $stack) {
        $result = $stack->pop();
        if ($stack->isEmpty()) {
            return $result;
        }
        $last = self::getAndRemoveLastElement($stack);
        $stack->push($result);
        return $last;
    }
}
 

* index.php

<?php

include './Stack.php';

$stack = new \ds\stack\Stack();
for ($i = 0; $i < 5; $i++) {
    $stack->push($i);
}
$stack->reverse();
while (!$stack->isEmpty()) {
    echo $stack->pop().PHP_EOL;
}

* test

$ php index.php 

0

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