BST.java: store value of getKey() for comparisons
BST.java: store value of getKey() for comparisons

Signed-off-by: Pang Yan Han <22594c345857f664c61cd411f607c4d40a9d4af9@gmail.com>

yanhan/cs2010,yanhan/cs2010,yanhan/cs2010,yanhan/cs2010