MyHashSet.php

<?php

namespace App;

/**
 * Design HashSet
 *
 * Design a HashSet without using any built-in hash table libraries.
 * Implement MyHashSet class:
 * - void add(key) Inserts the value key into the HashSet.
 * - bool contains(key) Returns whether the value key exists in the HashSet or not.
 * - void remove(key) Removes the value key in the HashSet. If key does not exist in the HashSet, do nothing.
 *
 * Example 1:
 * Input ["MyHashSet", "add", "add", "contains", "contains", "add", "contains", "remove", "contains"]
 * [[], [1], [2], [1], [3], [2], [2], [2], [2]]
 * Output [null, null, null, true, false, null, true, null, false]
 * Explanation
 * MyHashSet myHashSet = new MyHashSet();
 * myHashSet.add(1);      // set = [1]
 * myHashSet.add(2);      // set = [1, 2]
 * myHashSet.contains(1); // return True
 * myHashSet.contains(3); // return False, (not found)
 * myHashSet.add(2);      // set = [1, 2]
 * myHashSet.contains(2); // return True
 * myHashSet.remove(2);   // set = [1]
 * myHashSet.contains(2); // return False, (already removed)
 *
 * https://leetcode.com/problems/design-hashset
 */
class MyHashSet {
    private array $set = [];

    /**
     * @param int $key
     * @return void
     */
    public function add(int $key): void
    {
        if (!$this->contains($key)) {
            $this->set[] = $key;
        }
    }

    /**
     * @param int $key
     * @return void
     */
    public function remove(int $key): void
    {
        if ($this->contains($key)) {
            $keyIndex = array_search($key, $this->set, true);
            unset($this->set[$keyIndex]);
        }
    }

    /**
     * @param int $key
     * @return bool
     */
    public function contains(int $key): bool
    {
        if (in_array($key, $this->set, true)) {
            return true;
        }

        return false;
    }
}