Implement RemoveLastCommand's execute() method to remove source_list's last element.Step 4: Implement GroceryList's execute_undo() methodImplement GroceryList's execute_undo() method to do the following:Pop an UndoCommand off the undo stack• Execute the popped undo commandFile main.py has code that reads in a list of commands, one per line, that allow for basic testing of basic operations. So after implementingexecute_undo(), run your program with the following input:add bananasadd grapesadd strawberriesprintundoprintundoprintquitVerify that the corresponding output is:0. bananas1. grapes2. strawberries0. bananas1. grapes0. bananasThe program's output does not affect grading, so additional test cases can be added, if desired.Submitting code written so far to obtain partial credit is recommended before proceeding to the next step.Step 5: Implement the SwapCommand class and GroceryList's swap_with_undo() method Emport sysfrom GroceryList import GroceryListdef main():grocery_listifquitFalsewhile not quit:command=input()# Process user inputif command"print":elif 0 ==elif 0elif 0=grocery_list.print_list(sys.stdout)command.find("add "):grocery_list.add_with_undo (command [4:])command.find("removeat "):else:=grocery_list.remove_at_with_undo(int(command [9:]))parse_indices (command [5:])index2)nameelse:GroceryList()index1, index2else:grocery_list.swap_with_undo(index1,==if index2 < 0:print(""swap" command requires two indices, separated by a space. ex: swap 25')grocery_list. swap_with_undo(index1, index2)elif commandif 0else:command.find("swap "):1==elif commandquitgrocery_list.get_undo_stack_size():print("Cannot execute undo because undo stack is empty")=grocery_list.execute_undo()"quit":def parse_indices(str):"undo":Trueprint("unknown command: ", command)indices = [int(n) for n in str.split()]if len(indices) != 2:return -1, -1return indices_main__':

Class Definitions:Define the UndoAdd class with an execute method to undo adding an item.Define the…

Step 4: Implement GroceryList's execute_undo() method Implement GroceryList's execute_undo() method to do the following: • Pop an UndoCommand off the undo stack • Execute the popped undo command File main.py has code that reads in a list of commands, one per line, that allow for basic testing of basic operations. So after implementing execute_undo(), run your program with the following input: add bananas add grapes add strawberries print undo print undo print quit Verify that the corresponding output is: 0. bananas 1. grapes 2. strawberries 0. bananas 1. grapes 0. bananas The program's output does not affect grading, so additional test cases can be added, if desired. Submitting code written so far to obtain partial credit is recommended before proceeding to the next step. Step 5: Implement the SwanCommand class and Groceryl ist's swan with unde method

Step 4: Implement GroceryList's execute_undo() method Implement GroceryList's execute_undo() method to do the following: • Pop an UndoCommand off the undo stack • Execute the popped undo command File main.py has code that reads in a list of commands, one per line, that allow for basic testing of basic operations. So after implementing execute_undo(), run your program with the following input: add bananas add grapes add strawberries print undo print undo print quit Verify that the corresponding output is: 0. bananas 1. grapes 2. strawberries 0. bananas 1. grapes 0. bananas The program's output does not affect grading, so additional test cases can be added, if desired. Submitting code written so far to obtain partial credit is recommended before proceeding to the next step. Step 5: Implement the SwanCommand class and Groceryl ist's swan with unde method

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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A skip listThe second programming homework is already on a server (http://marmoset.famnit.upr.si).In this task, a skip list data structure should be implemented. You can follow the followinginstructions:- Implement the class NodeSkipList with two components, namely key node and arrayof successors. You can also add a constructor, but you do not need to add anymethod.- In the class SkipList implement a constructor SkipList(long maxNodes). The parameter maxNodes determines the maximal number of nodes that can be added to askip list. Using this parameter we can determine the maximal height of a node, thatis, the maximal length of the array of successors. As the maximal height of a nodeit is usually taken the logarithm of the parameter. Further, it is useful to constructboth sentinels of maximal height.- In the class SkipList it is useful to write a method which simulates coin flip andreturns the number of all tosses until the first head comes up. This number representsthe height of a node…
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Please use Java Write a method “removeBottomItemStack” that takes a stack of integers and removes the first item added (the one at the bottom).
Implement the following method using the Fork/JoinFramework to assign random values to the list.public static void parallelAssignValues(double[] list)Write a test program that creates a list with 9,000,000 elements and invokesparallelAssignValuesto assign random values to the list. Also implement asequential algorithm and compare the execution time of the two. Note if you useMath.random(), your parallel code execution time will be worse than the sequentialcode execution time because Math.random() is synchronized and cannot beexecuted in parallel. To fix this problem, create a Random object for assigningrandom values to a small list.
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Implement a simple linked list in Python (Write source code and show output) with basic linked list operations like: (a) create a sequence of nodes and construct a linear linked list. (b) insert a new node in the linked list. (b) delete a particular node in the linked list. (c) modify the linear linked list into a circular linked list. Use this template: class Node:def __init__(self, val=None):self.val = valself.next = Noneclass LinkedList:"""TODO: Remove the "pass" statements and implement each methodAdd any methods if necessaryDON'T use a builtin list to keep all your nodes."""def __init__(self):self.head = None # The head of your list, don't change its name. It shouldbe "None" when the list is empty.def append(self, num): # append num to the tail of the listpassdef insert(self, index, num): # insert num into the given indexpassdef delete(self, index): # remove the node at the given index and return the deleted value as an integerpassdef circularize(self): # Make your list circular.…
Implement PokerValue as specified in textbook page 417, problem 33(a). Your implementation must include following: 1. At least one ADT type selected from textbook files such as Stack, Queue, Collection and List for storing the poker hand. 2. Use only CardDeck.java to hold deck of cards, and Card.java to represent each card. GUI is not required. 3. Default constructor to create a five-card poker hand from CardDeck.java. Make sure the poker hand is implemented with one of the textbook ADT as set forth above. 4. Overloaded constructor accepts an array of five cards to initialize one poker hand. 5. toString() method outputs in the same format as shown in SampleActualOutput.txt 6. You may add other methods as necessary. 7. Test your PokerValue.java with supplied PokerGame.java. Submit PokerValue.java
Write a method called inversePrint. This method gets a head of a linkedlist and Recursively print from the last item to the first one. This is a Recursive method. If Recursive is not used you will get no mark for this question Do not reverse the linkedlist, only print it in reverse example call: in the main I will call your method like: buffer = myList.head; //This is a buffer to copy the head address inversePrint(buffer); After this, the order for myList should not changed. if myList has: 1->2->3->4->5 your function should print: 5-> 4 -> 3->2->1 but if I check myList the order should still be 1->2->3->4->5 you can assume the LinkedList code for all other operations exist and if you need you can use them Do Not create a new linkedlist in inverse Hint: use recursion does this for you really easy