php实现堆排序算法

╰半夏微凉° 2022-06-04 10:09 190阅读 0赞

最近在准备各种面试，复习了一波算法基础，关于什么是堆排序我就不多说了，这里说的很详细，不明白的可以参考一下：

https://jingyan.baidu.com/article/5225f26b057d5de6fa0908f3.html

废话不多说，贴完整代码：

<?php
    /**
     * Created by PhpStorm.
     * User: KeenSting
     * Date: 2017/12/7
     * Time: 下午5:47
     * Name: 梁小苍
     * Phone: 13126734215
     * QQ: 707719848
     * File Description: 堆排序
     */
    
    //节点类
    class Node{
        public $value;  //节点值
        public $left; //左子节点
        public $right; //右子节点
        public $father; //父节点
        public $pos_in_father; //在父节点的位置,左还是右
    
        public function __construct($num)
        {
            $this->value = $num;
            $this->left = $this->right = $this->father = null;
            $this->pos_in_father = null;//1 左,2右
        }
    }
    
    //测试堆排序类
    class ATest{
        private $list; //存放节点列表,节点间的关系用引用表示
        private $num;  //节点数
        private $result; //结果集
        public function __construct(array $data)
        {
            $this->list = $this->result = [];
            $this->num = count($data);
            $this->createHeap($data,$this->num);
            $this->initHeap();
        }
    
        //执行排序
        public function run()
        {
            //交换堆顶和堆尾的节点值,移除尾部节点,加入到输出中
            while(true)
            {
                $size = count($this->list);
                if($size>2)
                {
                    array_push($this->result,$this->list[0]->value);//堆顶的数加入结果集
                    $tail = array_pop($this->list);
                    $this->list[0]->value = $tail->value;//堆尾的数放到堆顶,在此调整
                    if($father = &$tail->father)//释放尾部节点,修改父节点中子节点信息,置null
                    {
                        if($tail->pos_in_father==1)
                            $father->left = null;
                        else
                            $father->right = null;
                    }
                    unset($tail);
                    $this->nodeAdjust($this->list[0]);
                    
                }else//只有两个元素的时候就释放掉
                {
                    array_push($this->result,$this->list[0]->value);
                    array_push($this->result,$this->list[1]->value);
                    unset($this->list);
                    break;
                }
            }
            //打印降序结果
            print_r($this->result);
            //打印升序结果
            print_r(array_reverse($this->result));
        }
        
        //创建堆结构,结果存放在list中,按从上到下,从左到右排列
        private function createHeap($data,$length)
        {
            //使用array_shift作为队列输出
            $root = new Node($data[0]);
            $queue = [];
            $index = 0;
            array_push($queue,$root);
    
            while($queue)
            {
                $father = array_shift($queue);
                $index++;
                if($index<$length)//创建左节点
                {
                    $node1 = new Node($data[$index]);
                    $father->left = $node1;
                    $node1->father = $father;
                    $node1->pos_in_father = 1;
                    array_push($queue,$node1);
                    $index++;
                }
                if($index<$length)//创建右节点
                {
                    $node2 = new Node($data[$index]);
                    $father->right = $node2;
                    $node2->father = $father;
                    $node2->pos_in_father = 2;
                    array_push($queue,$node2);
                }
    
                array_push($this->list,$father);
    
            }
    
        }
    
        //初始化为大顶堆
        private function initHeap()
        {
            for($i=$this->num-1;$i>=0;$i--)
            {
                $tmp = &$this->list[$i];
                $this->nodeAdjust($tmp);
            }
        }
    
        //递归调整节点以及其子节点,保证大顶堆的特性
        private function nodeAdjust(&$tmp)
        {
            if(($left = &$tmp->left)!=null)//左子树
            {
                if(($right = &$tmp->right)!=null)//右子树在
                {
    
                    if($right->value > $left->value)//先比较子节点大小
                    {
                        if($tmp->value < $right->value)//父节点和右节点交换
                        {
                            $tmp_val = $right->value;
                            $right->value = $tmp->value;
                            $tmp->value = $tmp_val;
                            $this->nodeAdjust($right);
                        }
                    }else
                    {
                        if($tmp->value < $left->value)//父节点和左节点交换
                        {
                            $tmp_val = $left->value;
                            $left->value = $tmp->value;
                            $tmp->value = $tmp_val;
                            $this->nodeAdjust($left);
                        }
                    }
                }else{
       //没有右子树
    
                    if($tmp->value < $left->value)
                    {
    
                        $tmp_val = $left->value;
                        $left->value = $tmp->value;
                        $tmp->value = $tmp_val;
                        $this->nodeAdjust($left);
                    }
                }
            }else
                echo '不存在子树----';
    
        }
    }
    
    $a = new ATest([3,1,9,2,7,6,11,5,4,13]);
    $a->run();

执行结果如下：

Array

(

\[0\] => 13

\[1\] => 11

\[2\] => 9

\[3\] => 7

\[4\] => 6

\[5\] => 5

\[6\] => 4

\[7\] => 3

\[8\] => 2