<?php

// your code goes here
// Author: Nayaka Ghana Subrata

class Kamus{
	private $arr = [];
	
	public function tambah(string $kata, array $sinonim): void{
		if (!isset($this->arr[$kata])){
			$this->arr[$kata] = [];
		}
		
		foreach ($sinonim as $s){
			$this->arr[$kata][$s] = true;
			if (!isset($this->arr[$s])){
				$this->arr[$s] = [];
			}
			$this->arr[$s][$kata] = true;
		}
	}
	
	public function ambilSinonim(string $kata): ?array{
		if (!isset($this->arr[$kata])){
			return null;
		}
		return array_keys($this->arr[$kata]);
		
	}
}


// testing
$kamus = new Kamus();

$kamus->tambah("big", ["large", "great"]);
$kamus->tambah("big", ["huge", "fat"]);
$kamus->tambah("huge", ["enormous", "gigantic"]);

print_r($kamus->ambilSinonim("big"));
print_r($kamus->ambilSinonim("huge"));
print_r($kamus->ambilSinonim("gigantic"));
var_dump($kamus->ambilSinonim("colossal"));
?>