* 参照php标准库设计接口
http://php.net/manual/en/class.spldoublylinkedlist.php
* 反转单向链表
reverse方法, 其他的方法为了方便测试
<?php /** * Created by PhpStorm. * User: Mch * Date: 8/11/18 * Time: 00:25 */ class Node { public $value; public $next; public function __construct($data) { $this->value = $data; $this->next = null; } } class LinkedList implements Iterator, Countable { private $head; private $cur; public function __construct() { $this->head = $this->cur = null; } public function isEmpty() { return is_null($this->head); } public function count() { $p = $this->head; $count = 0; while ($p !== null) { $p = $p->next; $count++; } return $count; } public function current() { if ($this->isEmpty()) { return null; } return $this->cur->value; } public function next() { if (is_null($this->cur)) { return null; } $this->cur = $this->cur->next; } public function rewind() { $this->cur = $this->head; } public function valid() { return !is_null($this->cur); } public function key() { $p = $this->head; $key = 0; while ($p !== $this->cur) { $p = $p->next; $key++; } return $key; } public function push($value) { if ($this->isEmpty()) { $this->head = new Node($value); $this->cur = $this->head; } else { $this->cur = $this->head; while ($this->cur->next !== null) { $this->cur = $this->cur->next; } $this->cur->next = new Node($value); } return $this; } public function forEach(callable $callback, mixed $userdata = null) { $this->rewind(); while($this->valid()) { call_user_func($callback, $this->current(), $this->key(), $userdata); $this->next(); } } public function reverse() { if ($this->isEmpty()) return; if ($this->count() < 2) return; $prev = null; $cur = $this->head; while ($cur) { // save next $next = $cur->next; // move cur to head $this->head = $cur; $cur->next = $prev; // iterate $prev = $cur; $cur = $next; } } }
* test
$list = new LinkedList(); for ($i = 65; $i < 91; $i++) { $list->push(chr($i)); } $list->forEach(function($value, $index) { printf("[%d] => %s<br />", $index, $value); }); echo ‘-------------------<br />‘; $list->reverse(); $list->forEach(function($value, $index) { printf("[%d] => %s<br />", $index, $value); });
* output:
[0] => A
[1] => B
[2] => C
[3] => D
[4] => E
[5] => F
....
-------------------
[0] => Z
[1] => Y
[2] => X
[3] => W
[4] => V
[5] => U
...
原文地址:https://www.cnblogs.com/mingzhanghui/p/9462187.html
时间: 2024-10-07 14:14:50