Calc all the rectangles by points on the plane (Google interview)

!index.php

<?php

require 'Point.php';
require 'PointArray.php';
require 'Rectangle.php';

$points = new PointArray([
    [0, 0], [0, 1], [0, 2], [0, 3],
    [1, 0], [1, 1], [1, 2], [1, 3],
    [2, 0], [2, 1], [2, 2], [2, 3],
    [3, 0], [3, 1], [3, 2], [3, 3],
]);

$rectangles = [];

for ($i = 0; $i < $points->count(); $i++) {
    for ($j = $i; $j < $points->count(); $j++) {
        $point1 = $points->index($i);
        $point2 = $points->index($j);
        
        if ($point2->verticalTo($point1) || $point2->horizontalTo($point1)) continue;
        
        $rectExtraPoint1 = new Point($point1->x(), $point2->y());
        $rectExtraPoint2 = new Point($point2->x(), $point1->y());
        
        $isExtraPoint1 = $points->search($rectExtraPoint1);
        $isExtraPoint2 = $points->search($rectExtraPoint2);
        
        if ($isExtraPoint1 && $isExtraPoint2) {
            $rectangle = new Rectangle($point1, $point2, $rectExtraPoint1, $rectExtraPoint2);
            $hash = $rectangle->getHash();
            
            if (isset($rectangles[$hash])) continue;
            
            $rectangles[$hash] = $rectangle;
        }
    }
}

echo count($rectangles);

Point.php

<?php

class Point
{
    private $x;
    private $y;
    
    function __construct($x, $y)
    {
        $this->x = $x;
        $this->y = $y;
    }
    
    public function x()
    {
        return $this->x;
    }
    
    public function y()
    {
        return $this->y;
    }
	
    public function verticalTo($point)
    {
        return $this->x() === $point->x();
    }
	
    public function horizontalTo($point)
    {
        return $this->y() === $point->y();
    }
    
    public function equalTo($point)
    {
        return $this->x() === $point->x() && $this->y() === $point->y();
    }
}

PointArray.php

<?php

class PointArray
{
    private $pointArray;
    
    function __construct($pointArray)
    {
        foreach ($pointArray as $point) {
            $this->pointArray[] = new Point($point[0], $point[1]);
        }
    }
    
    public function getPoints()
    {
        return $this->pointArray;
    }
    
    public function count()
    {
        return count($this->pointArray);
    }
    
    public function index($i)
    {
        return $this->pointArray[$i];
    }
    
    public function search($needlePoint)
    {
        foreach ($this->pointArray as $point) {
            if ($point->equalTo($needlePoint)) {
                return true;
            }
        }
        
        return false;
    }
}

Rectangle.php

<?php

class Rectangle
{
    private $point1;
    private $point2;
    private $point3;
    private $point4;
    
    function __construct($point1, $point2, $point3, $point4)
    {
        $this->point1 = $point1;
        $this->point2 = $point2;
        $this->point3 = $point3;
        $this->point4 = $point4;
    }
    
    public function getHash()
    {
        $xs = [$this->point1->x(), $this->point2->x(), $this->point3->x(), $this->point4->x()];
        $ys = [$this->point1->y(), $this->point2->y(), $this->point3->y(), $this->point4->y()];
        
        $xmin = min($xs);
        $xmax = max($xs);
        $ymin = min($ys);
        $ymax = max($ys);
        
        return md5($xmin.$ymin.$xmax.$ymax);
    }
}