CSE110 - Assignment #7  - Solved

Topics
•         Array (Chapter 6)  

-   Array object as an instance variable   

-   Array operations  

 Use the following Guidelines: 

•         Give identifiers semantic meaning and make them easy to read (examples numStudents, grossPay, etc).  

•         Keep identifiers to a reasonably short length.  

•         User upper case for constants. Use title case (first letter is upper case) for classes. Use lower case with uppercase word separators for all other identifiers (variables, methods, objects).  

•         Use tabs or spaces to indent code within blocks (code surrounded by braces). This includes classes, methods, and code associated with ifs, switches and loops. Be consistent with the number of spaces or tabs that you use to indent.  

•         Use white space to make your program more readable.  

 


Part# 1: CodingBat.com Exercise: (5 pts)
 

Go to the following sites and do the exercises. If you solve the question, post the code as a comment in the part #2 code. 

 

a)      swapEnds: https://codingbat.com/prob/p118044 

b)      commonEnd: https://codingbat.com/prob/p191991 

c)      countEvens: https://codingbat.com/prob/p162010 

d)      sum13: https://codingbat.com/prob/p127384 

e)      fix34: https://codingbat.com/prob/p159339 

Note:  

The answers to the five questions (a through e) above should be typed in the block of comments in the CardList.java file such as; 

/*** Part#1 Asnswer  

a)  public int[] swapEnds(int[] nums) { ...   

} 

 

b)  … 

… 

*/ 

                 

Part#2: Programming (15 pts)  
Your assignment is to write  two java files. One is a class definition named CardList (CardList.java), and another is the test driver program, Assignment7.java.  

 

1) The CardList is a class to keep the trump cards, and it has the two instance variables: cards and history. 

 

CardList 
-  cards      : char[] 

-  history    : String 
+ CardList(int) 

+ flip()              : void 

+ shift()             : void 

+ shuffle()           : void 

+ change(int size)    : void 

- shuffleIndex()      : int[] 

+ getHistory ()       : String 
 

The cards is an array object storing characters among A234567890JQK. The 'A' is for 

Ace, '2' is for two, '3' is three, .... '0' is for ten, 'J' is for Jack, 'Q' is for queen, and 'K' is for king like trump cards. The history is the record of updates. 

 

The class must include the constructors and methods below: (If your class does not contain any of the following methods, points will be deducted). The public and private access modifiers are represented as "+" and "-" respectively. 

 

1. CardList(int numberOfCard): (2 pts) 
The constructor is to create an char-type array with the length of first input parameter.  Each element in the array is initialized as a random character such as cards[0] = '3', cards[1] = 'Q', and cards[2]= 'A'.  

 

2. flip():void  (2 pts) 
This method is to flip the order of elements in cards.  For example, the cards is 

flipped from {'3', '4', '5', '6', '7', '8'} to {'8', '7', '6', '5', '4', '3'} after this method is called.  

*) When it is called, update the history by adding the new list of cards and name of operation (look at the getHistory () below). 

 

3. shift():void  (2 pts) 
This method is to shift the position of each element in cards one by one.  For example, the cards {'5', '7', '8', '6', '4'} is updated to {'7', '8', '6', '4', '5'} by shift(). The element out of range is moved to the end of array such as cards[0] →cards[-1] (this is out of range) → cards[cards.length1].  

*)When it is called, update the history by adding the new list of cards and name of operation (look at the getHistory () below). 

 

4. shuffle():void  (2 pts or 4 pts) 

(2 pts without shffleIndex()) 
This method is to shuffle all elements in cards randomly. *) When it is called, update the history by adding the new list of cards and name of operation (look at the getHistory () below). 

(4 pts with shffleIndex()) 
The following can be realized with the completed version of shuffleIndex() below. 

Any elements MUST NOT be in the same position as before. For example, it is OK 

to shuffle the cards from {'0', 'A', '2', '3', '4'} to {'4', '2', 'A', '0', '3'}. However, {'4', 'A', '2', '0', '3'} is not accepted because 'A' and '2' are not changed from the 2nd and 

3rd positions.  Before coding, look at and use the shuffleIndex() below. 

When more than half of elements have a same card, the output may looks invalid.  Tips: Calculate the shuffuled index list such as 

 int[] pos = shuffuleIndex(),  
 and update each card cards[i] using the value of card[ pos[i] ]; 

For example, the pos[0] must be some number except 0, so we can use the pos[0] as the index of swapping target.  

                         

5. change(int num): (2 pts) 
This method is to change some of cards by replacing random values among A234567890JQK. The number of cards to change is defined by the input num. 

Always the change starts from the first element cards[0]to cards[num-1]  

The change(3) changes three cards such as from {'Q', 'J', '4', '5', 'A'} to {'1', '5', '3', '5', 'A'}, because the high-lightened three items are changed. In the method, check the validity (positive and less than the length of cards) of num first, and if it is not valid, do nothing. 

*) When it is called, update the history by adding the new list of cards and name of operaution (look at the getHistory () below). 

 

6. shuffleIndex ():int[] (To get 4-pts in the shuffle()) 
This method is to return an array of shuffled integers, which will be used to shuffle all cards. The size is the same as the cards.length. Any element in the array MUST NOT be the same as the position index. Suppose that the input size is 5. The output should be initialized as {0, 1, 2, 3, 4}, and shuffle elements repeatedly and check the validity before returning it. For example, {1, 3, 4, 2, 0} is valid, because the output[0] = 1, output[1] = 3, ... output[4] = 0. All values are different from the index (position value).  

However {2, 1, 3, 4, 0} is not accepted because the 1 is in the position [1] is the array. By using while-loop, swap random two elements until all become different from the index. Use this private method in shuffle(). 

 

7. getHisotry(): String (2 pts) 
Return the history, which has all history of operations line by line ("\n" : line change). It is OK to use Arrays.toString(cards). 

 

            [Q, 6, 7, 4, 8, A, 0]         [A, 3, 5, 4, 8, A, 0]: Change [0, A, 8, 4, 5, 3, A]: Flip [A, 8, 4, 5, 3, A, 0]: Shift [8, 4, 3, A, 0, A, 0]: Shuffle
 

2) Write the test driver called Assignment7.java. (1 pts)  Assignment7.java contains the main method to create a CardList instance object and test the methods in the class.  The program will ask a user to enter one of the commands. Based on the user's choice, the program needs to perform corresponding operation. This will be done by calling (invoking) one of the methods you defined in the class. It will terminate when the user enters 'q'. The tester program provided in the last assignments may help. In addition to the main method, the Assignment7 class has a static method, printMenu(), to print out the following commands  

 

Command Options 

----------------------------------- a: Create new cards b: flip the cards c: shift  the cards d: shuffle the cards e: change the cards ?: Display the menu again 

q: Quit this program 

 

Here is the description for each option: 

a: ask & read the size of array, and create new object and display the elements b: flip and display the history of operations c: shift and display the history of operations d: shuffle and display the history of operations e: ask & read the size of cards to change, and display the history of operations. 

?: display the menu 

q: quits the program 

 

 

Output Example 
•      Input in red is not shown when you submit online 

•      This program uses many random values. So the output here should be different from your output.  

---------------- INPUT 1 ---------------- a 5 b c d e 3 ? q 

 

---------------- 

YOUR OUTPUT 1 

---------------- 

*** Start of Program *** 

 

Command Options 

----------------------------------- a: Create new cards b: flip the cards c: shift the card  d: shuffle the cards  e: change the cards ?: Display the menu again q: Quit this program 

 

 

Please enter a command or type ? a     a [Create new cards] 

    [Input the size of cards]: 5 

[8, Q, 2, 6, 5] 

 

Please enter a command or type ? b     b [flip the cards] [8, Q, 2, 6, 5] 

[5, 6, 2, Q, 8]: Flip 

 

Please enter a command or type ? c     c [shift the cards] [8, Q, 2, 6, 5] 

[5, 6, 2, Q, 8]: Flip 

[6, 2, Q, 8, 5]: Shift 

Please enter a command or type ? d 

    c [shuffle the cards] [8, Q, 2, 6, 5] 

[5, 6, 2, Q, 8]: Flip 

[6, 2, Q, 8, 5]: Shift 

[8, 6, 2, 5, Q]: Shuffle 

 

Please enter a command or type ? e     e [Change the cards] 

    [Input the number of cards to change]:3 

[8, Q, 2, 6, 5] 

[5, 6, 2, Q, 8]: Flip 

[6, 2, Q, 8, 5]: Shift 

[8, 6, 2, 5, Q]: Shuffle 

[8, 4, 7, 5, Q]: Change 

 

Please enter a command or type ? ? Command Options 

----------------------------------- a: Create new cards b: flip the cards c: shift the card  d: shuffle the cards  e: change the cards ?: Display the menu again q: Quit this program 

 

 

Please enter a command or type ? q 

*** End of Program ***