DesignHashMap.php

<?php

namespace App;

/**
 * Design HashMap
 *
 * Design a HashMap without using any built-in hash table libraries.
 * Implement the MyHashMap class:
 * - MyHashMap() initializes the object with an empty map.
 * - void put(int key, int value) inserts a (key, value) pair into the HashMap. If the key already exists in the map,
 * update the corresponding value.
 * - int get(int key) returns the value to which the specified key is mapped, or -1 if this map contains no mapping for
 * the key.
 * - void remove(key) removes the key and its corresponding value if the map contains the mapping for the key.
 *
 * Example 1:
 * Input ["MyHashMap", "put", "put", "get", "get", "put", "get", "remove", "get"]
 * [[], [1, 1], [2, 2], [1], [3], [2, 1], [2], [2], [2]]
 * Output [null, null, null, 1, -1, null, 1, null, -1]
 * Explanation
 * MyHashMap myHashMap = new MyHashMap();
 * myHashMap.put(1, 1); // The map is now [[1,1]]
 * myHashMap.put(2, 2); // The map is now [[1,1], [2,2]]
 * myHashMap.get(1);    // return 1, The map is now [[1,1], [2,2]]
 * myHashMap.get(3);    // return -1 (i.e., not found), The map is now [[1,1], [2,2]]
 * myHashMap.put(2, 1); // The map is now [[1,1], [2,1]] (i.e., update the existing value)
 * myHashMap.get(2);    // return 1, The map is now [[1,1], [2,1]]
 * myHashMap.remove(2); // remove the mapping for 2, The map is now [[1,1]]
 * myHashMap.get(2);    // return -1 (i.e., not found), The map is now [[1,1]]
 *
 * https://leetcode.com/problems/design-hashmap
 */
class DesignHashMap
{
    /** @var int[] */
    private array $map = [];
    /**
     * @param int $key
     * @param int $value
     * @return void
     */
    public function put(int $key, int $value): void
    {
        $this->map[$key] = $value;
    }

    /**
     * @param int $key
     * @return int
     */
    public function get(int $key): int
    {
        return $this->map[$key] ?? -1;
    }

    /**
     * @param int $key
     * @return void
     */
    public function remove(int $key): void
    {
        unset($this->map[$key]);
    }
}