[2019 카카오 개발자 겨울 인턴십] 호텔 방 배정

import java.util.HashMap;
import java.util.Map;

class Solution {
    public long[] solution(long k, long[] room_number) {
        long[] answer = new long[room_number.length];

        Map<Long, Long> map = new HashMap<>();
        
        for(int i = 0; i < room_number.length; i++) {
        	answer[i] = getRoomNumber(map, room_number[i]);
        }
        
        return answer;
    }
    
    static long getRoomNumber(Map<Long, Long> map, long n) {
    	if(map.get(n) == null) {
    		map.put(n , n + 1);
    		return n;
    	}
    	else {
    		long res = getRoomNumber(map, map.get(n));
    		map.replace(n , res + 1);
    		return res;
    	}
    }
}