Union find [algorithm]

union_find.php

<?php

class UnionFind
{
    /**
     * Elements
     * @var array
     */
    public $elements;

    /**
     * Add a new set
     * 
     * @param $x
     * @return void
     */
    public function addSet($x)
    {
        $this->elements[$x] = $x;
    }

    /**
     * Find 
     *
     * @param integer $x
     * @return integer
     */
    public function find($x)
    {
        if ($this->elements[$x] == $x) {
            return $x;
        }

        return $this->elements[$x] = $this->find($this->elements[$x]);
    }

    /**
     * Union
     * 
     * @param integer $x
     * @param integer $y
     * @return void
     */
    public function union($x, $y)
    {
        $x = $this->find($x);
        $y = $this->find($y);

        if (rand(0, 1000) % 2 == 0) {
            $this->elements[$x] = $y;
            return;
        }

        $this->elements[$y] = $x;
    }
}