CMPSCI 230 Discussion 1. Virtual Box and HW0

Transcription

1 CMPSCI 230 Discussion 1 Virtual Box and HW0 1

2 Contact Info Name: Kaituo Li Communicate through Piazza questions/posts to entire class or private messages to instructors Under extreme circumstances contact via Office hours: Thursday 4:30-6:00 PM, LGRT T223 2

3 INSTALL VIRTUAL BOX 3

4 Install VirtualBox 4

5 VirtualBox setup Download the ova file from course webpage and 1) Double click the ova file 2) Or alternatively select "File" -> "Import appliance" from the Manager window. 5

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10 Possible reasons for VirtualBox errors and workarounds Cannot launch VM Corrupt ova Redownload Antivirus package, esp. on Windows hosts Use the newest version Cannot connect to the Internet Adjust network setting (e.g. networking modes) Cannot download with browser in VirtualBox Try another browser (Chromium vs. Firefox) 10

11 Backup data when using VirtualBox Not as stable as non-virtualization product Example backup technologies Dropbox Google drive github USB flash drive Must be private, not public 11

12 Must I use the Lubuntu image you provided? Yes Different Linux version could give different errors and different output Different JDKs produce slightly different bytecode 12

13 i-clicker question What is *not* true about virtual box? A. Certain antivirus package may influence the use of virtual box B. You cannot run multiple operating systems at the same time using virtual box. C. There are chances that different JDKs in different virtual machine produce slightly different bytecode. D. Virtual box is not a fail-proof and safe way to store your data. 13

14 HW0 14

15 Linked List Node Definition: public class ListNode { int = -1; private ListNode = null; public void setnext (final ListNode ) { this. = ; public ListNode getnext () { return ;

16 Linked List Node Definition: public class ListNode { int = -1; private ListNode = null; public void setnext (final ListNode ) { this. = ; public ListNode getnext () { return ; A recursive data type

17 Assignment 0 Implement bounded sets using linked list A set is container Duplicate s are removed Bounded: fixed size

18 Creates a bounded int set The code is from starting jar file: public ListBoundedIntSet (final int [] elements) { ListNode current = null; int i = elements.length; while (--i >= 0) { final ListNode node = new ListNode(); node.setnext(current); node. = elements[i]; current = node; head = current;

19 Creates a bounded int set The code is from starting jar file: public ListBoundedIntSet (final int [] elements) { ListNode current = null; int i = elements.length; while (--i >= 0) { final ListNode node = new ListNode(); node.setnext(current); node. = elements[i]; current = node; head = current; x

20 Creates a bounded int set The code is from starting jar file: public ListBoundedIntSet (final int [] elements) { ListNode current = null; int i = elements.length; while (--i >= 0) { final ListNode node = new ListNode(); node.setnext(current); node. = elements[i]; current = node; head = current; x 1

21 Creates a bounded int set The code is from starting jar file: public ListBoundedIntSet (final int [] elements) { ListNode current = null; int i = elements.length; while (--i >= 0) { final ListNode node = new ListNode(); node.setnext(current); node. = elements[i]; current = node; head = current; x 1

22 Creates a bounded int set The code is from starting jar file: public ListBoundedIntSet (final int [] elements) { ListNode current = null; int i = elements.length; while (--i >= 0) { final ListNode node = new ListNode(); node.setnext(current); node. = elements[i]; current = node; head = current; x 2 1

23 Creates a bounded int set The code is from starting jar file: public ListBoundedIntSet (final int [] elements) { ListNode current = null; int i = elements.length; while (--i >= 0) { final ListNode node = new ListNode(); node.setnext(current); node. = elements[i]; current = node; head = current; x 2 1

24 Creates a bounded int set The code is from starting jar file: public ListBoundedIntSet (final int [] elements) { ListNode current = null; int i = elements.length; while (--i >= 0) { final ListNode node = new ListNode(); node.setnext(current); node. = elements[i]; current = node; head = current; x 3 2 1

25 Creates a bounded int set The code is from starting jar file: public ListBoundedIntSet (final int [] elements) { ListNode current = null; int i = elements.length; while (--i >= 0) { final ListNode node = new ListNode(); node.setnext(current); node. = elements[i]; current = node; head = current; x head

26 Another way of creating a bounded int set public ListBoundedIntSet (final int size) { ListNode current = null; int i = size; while (--i >= 0) { final ListNode node = new ListNode(); node.setnext(current); current = node; head = current;

27 Another way of creating a bounded int set public ListBoundedIntSet (final int size) { ListNode current = null; int i = size; while (--i >= 0) { final ListNode node = new ListNode(); node.setnext(current); current = node; head = current; x head

28 Task #1: Implement pulltohead head prev curr x

29 Task #1: Implement pulltohead head prev curr x 1) take the immediate successor after curr and assign it to prev.

30 Task #1: Implement pulltohead head prev curr x 1) take the immediate successor after curr and assign it to prev. 2) make curr. point to the original head

31 Task #1: Implement pulltohead head prev curr x 1) take the immediate successor after curr and assign it to prev. 2) make curr. point to the original head 3) make curr the new head

32 Task #1: Implement pulltohead head prev curr x 1) take the immediate successor after curr and assign it to prev. 2) make curr. point to the original head 3) make curr the new head Question: What if curr is at the head of the list? What if curr is null?

33 Task #2: Fix contains public boolean contains (final int ) { ListNode prev = null; ListNode curr = head; while (true) { if (curr == null curr. == -1) { return false; else if (curr. == ) { return true; else { prev = curr; curr = curr.getnext(); Three possible results: The was present The was not present We reach the end of the list We reach an empty node (If we create the set using ListBoundedIntSet (final int size))

34 Task #2: Fix contains public boolean contains (final int ) { ListNode prev = null; ListNode curr = head; while (true) { if (curr == null curr. == -1) { return false; else if (curr. == ) { return true; else { prev = curr; curr = curr.getnext(); Three possible results: The was present The was not present We reach the end of the list We reach an empty node (If we create the set using ListBoundedIntSet (final int size))

35 Task #3 Implement add 1. Search for the node containing the to add 2. Three possible results: If the was present already, do nothing If the was not present If the list is not full, add the to the empty node If the list is full, change the of the node at the end of the list to be the new 3. Pull the affected node to the head of the list

36 Task #3 Implement add 1. Search for the node containing the to add 2. Three possible results: If the was present already, do nothing If the was not present If the list is not full, add the to the empty node If the list is full, change the of the node at the end of the list to be the new 3. Pull the affected node to the head of the list

37 i-clicker question What does the code do? public ListNode foo(listnode head) { ListNode pre = null; while(head!=null) { ListNode temp = head.; head. = pre; pre = head; head = temp; return pre; A. Reverse a singly linked list. B. Sort a singly linked list. C. Rotate a singly linked list by 1 place. D. Remove a node from a linked list.