108 lines
2.7 KiB
PHP
108 lines
2.7 KiB
PHP
<?php
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class SNode
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{
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//数据域
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public $data;
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//指针域，引用SNode对象
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public $next = [];
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public function __construct($data = null)
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{
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$this->data = $data;
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}
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//获取当前节点索引层数
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public function getMaxLevel()
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{
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return count($this->next) - 1;
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}
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}
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class SkipList
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{
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//索引最大层数
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public $indexLevel;
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//头节点
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protected $head;
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public function __construct(int $indexLevel)
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{
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$this->indexLevel = max($indexLevel, 0);
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$this->head = new SNode();
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}
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public function addData($data)
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{
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$newNode = new SNode($data);
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for ($level = $this->getRandomLevel(), $node = $this->head; $level >= 0; $level--) {
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while (isset($node->next[$level]) && $data < $node->next[$level]->data) {
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$node = $node->next[$level];
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}
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if (isset($node->next[$level])) {
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$newNode->next[$level] = $node->next[$level];
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}
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$node->next[$level] = $newNode;
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}
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return $newNode;
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}
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public function deleteData($data)
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{
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$deleted = false;
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for ($level = $this->head->getMaxLevel(), $node = $this->head; $level >= 0; $level--) {
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while (isset($node->next[$level]) && $data < $node->next[$level]->data) {
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$node = $node->next[$level];
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}
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if (isset($node->next[$level]) && $data == $node->next[$level]->data) {
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$node->next[$level] = isset($node->next[$level]->next[$level]) ?
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$node->next[$level]->next[$level] : null;
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$deleted = true;
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}
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}
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return $deleted;
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}
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public function findData($data)
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{
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for ($level = $this->head->getMaxLevel(), $node = $this->head; $level >= 0; $level--) {
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while (isset($node->next[$level]) && $data < $node->next[$level]->data) {
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$node = $node->next[$level];
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}
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if (isset($node->next[$level]) && $data == $node->next[$level]->data) {
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return $node->next[$level];
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}
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}
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return false;
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}
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protected function getRandomLevel()
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{
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return mt_rand(0, $this->indexLevel);
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}
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}
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/**
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* 示例
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*/
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$indexLevel = 2;
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$skipList = new SkipList($indexLevel);
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for ($i = 10; $i >= 0; $i--) {
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$skipList->addData($i);
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}
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//打印0到10组成的跳表
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var_dump($skipList);
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//返回SNode对象
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var_dump($skipList->findData(5));
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$skipList->deleteData(5);
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//返回false
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var_dump($skipList->findData(5)); |