$2.$ Complete method unzip$()$ in SinglyLinkedList.java

$3.$ What is the running time of the following two programs on a linked list with n elements:

$($a$)$ for$($x: list$)\{$ print x $\}/*$ using the iterator $*/$

$/*$ same as: it $=$ list.iterator$()$; while$($it$.$hasNext$())\{$ print it$.$next$()\}*/$

$($b$)$ for$($i$=0$; i