Pretend to use array (but we need linked list here)
Pretend to use array (but we need linked list here)
oops
Revert "Pretend to use array (but we need linked list here)"

This reverts commit 82d00f4aacbd26709413be1b3d1bf7c0e57d8ee9.

Conflicts:
	assignment-2_queues/Deque.java
start constructing test cases