Leetcode PHP题解--D78 206. Reverse Linked List

<?php

/**

 * Definition for a singly-linked list.

 * class ListNode {

 *     public $val = 0;

 *     public $next = null;

 *     function __construct($val) { $this->val = $val; }

 * }

 */

class Solution {

    /**

     * @param ListNode $head

     * @return ListNode

     */

    function reverseList($head) {

        $stack = [];

        while(true){

            $stack[] = $head;

            $head = $head->next;

            if(is_null($head)){

                break;

            }

        }

        $root = $head = array_pop($stack);

        while($stack){

            $head->next = array_pop($stack);

            $head = $head->next;

        }

        $head->next = null;

        return $root;

    }

}