124 lines
2.8 KiB
PHP
124 lines
2.8 KiB
PHP
<?php
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/**
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* File: array_queue.php
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* Created Time: 2024-05-19
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* Author: DoWake (admin@mengxing.cc)
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*/
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/* 基于环形数组实现的队列 */
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class ArrayQueue
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{
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private $nums; // 用于存储队列元素的数组
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private $front; // 队首指针，指向队首元素
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private $queSize; // 队列长度
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/* 构造方法 */
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public function __construct($capacity)
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{
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$this->nums = array_fill(0, $capacity, 0);
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$this->front = 0;
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$this->queSize = 0;
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}
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/* 获取队列的容量 */
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public function capacity()
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{
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return count($this->nums);
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}
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/* 获取队列的长度 */
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public function size()
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{
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return $this->queSize;
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}
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/* 判断队列是否为空 */
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public function isEmpty()
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{
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return $this->queSize === 0;
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}
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/* 入队 */
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public function push($num)
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{
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if ($this->queSize === $this->capacity()) {
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echo '队列已满' . PHP_EOL;
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return;
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}
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// 计算队尾指针，指向队尾索引 + 1
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// 通过取余操作实现 rear 越过数组尾部后回到头部
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$rear = ($this->front + $this->queSize) % $this->capacity();
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// 将 num 添加至队尾
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$this->nums[$rear] = $num;
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$this->queSize++;
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}
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/* 出队 */
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public function pop()
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{
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$num = $this->peek();
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// 队首指针向后移动一位，若越过尾部，则返回到数组头部
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$this->front = ($this->front + 1) % $this->capacity();
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$this->queSize--;
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return $num;
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}
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/* 访问队首元素 */
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public function peek()
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{
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if ($this->isEmpty()) {
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throw new Exception('The Quque Is Empty.');
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}
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return $this->nums[$this->front];
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}
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/* 返回数组 */
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public function toArray()
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{
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// 仅转换有效长度范围内的列表元素
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$res = [];
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for ($i = 0, $j = $this->front; $i < $this->queSize; $i++, $j++) {
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$res[$i] = $this->nums[$j % $this->capacity()];
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}
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return $res;
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}
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}
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/* Driver Code */
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/* 初始化队列 */
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$capacity = 10;
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$queue = new ArrayQueue($capacity);
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/* 元素入队 */
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$queue->push(1);
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$queue->push(3);
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$queue->push(2);
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$queue->push(5);
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$queue->push(4);
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echo '队列 queue = [' . join(', ', $queue->toArray()) . ']' . PHP_EOL;
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/* 访问队首元素 */
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$peek = $queue->peek();
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echo "队首元素 peek = {$peek}" . PHP_EOL;
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/* 元素出队 */
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$pop = $queue->pop();
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echo "出队元素 pop = {$pop}，出队后 queue = [" . join(', ', $queue->toArray()) . "]" . PHP_EOL;
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/* 获取队列的长度 */
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$size = $queue->size();
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echo "队列长度 size = {$size}" . PHP_EOL;
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/* 判断队列是否为空 */
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$isEmpty = $queue->isEmpty();
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$isEmptyStr = $isEmpty ? 'true' : 'false';
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echo "队列是否为空 = {$isEmptyStr}" . PHP_EOL;
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/* 测试环形数组 */
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for ($i = 0; $i < 10; $i++) {
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$queue->push($i);
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$queue->pop();
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echo "第 {$i} 轮入队 + 出队后 queue = [" . join(', ', $queue->toArray()) . "]" . PHP_EOL;
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}
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