https://tourspace.tistory.com/42 https://www.javatpoint.com/memory-management-in-java
arraydeque vs arraylist 성능은 확장시 사이즈가 100%, 50% 씩 늘어나서 그 만큼 차이남
https://yeon-kr.tistory.com/113
https://steady-coding.tistory.com/584