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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I need some help making this code more simple. 2) AlgorithmtokenList = "{}()[]"initialize stack to emptyGet file name from user: fileNameOpen the file (fileName)read line from fileName into strLinewhile not EOF (end of file)find tokenList items in strLine for each token in strLineif token = "[" thenpush "]" into stackelse if token = "(" thenpush ")" into stackelse if token = "{" thenpush "}" into stackelse if token = "]" OR token = ")" OR token = "}" thenpop stack into poppedTokenif poppedToken not equal tokenprint "Incorrect Grouping Pairs"exitend ifend ifnext tokenend whileif stack is emptyprint "Correct Grouping Pairs"elseprint "Incorrect Grouping Pairs"end if
Create an application that reads a statement from the user and outputs it with the characters of each word reversed. To reverse the letters in each phrase, use a stack.
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This is the wrong output. Please look at the expected output that is attached. And print out the expected output with the correct code.
In Java Integer in is read from input. Write a while loop that iterates until in is less than or equal to 0. In each iteration: Update in with the quotient of in and 7. Output the updated in, followed by a newline. Click here for exampleEx: If the input is 2401, then the output is: 343 49 7 1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 import java.util.Scanner; public class QuotientCalculator { publicstaticvoidmain(String[] args) { Scannerscnr=newScanner(System.in); intin; in=scnr.nextInt(); /your code here/ } }
n most personal computers, the largest integer is 32,767 and the largest long integer is 2,147,483,647. Some applications, such as the national debt, may require an unbounded integer. One way to store and manipulate integers of unlimited size is by using a linked list. Each digit is stored in a node of the list. For example, the figure below shows how we could store a five-digit number in a linked list.39While the linked list in the figure is represented as moving from right to left, remember that there is no physical direction in a linked list. We represent it this way to assist us inunderstanding the problem.To add two numbers, we simply add the corresponding digit in the same location in their respective linked lists with the carry from the previous addition. With each addition, if the sum is greater than 10, then we need to subtract ten and set the carry to one. Otherwise, the carry is set to zero.Write a program to add two integer linked lists. Design your solution so that the…
Write a program that obtains the executiontime of external sorts for integers of size 6,000,000, 12,000,000, 18,000,000,24,000,000, 30,000,000, and 36,000,000. Your program should print a tablelike this:
Write a java program to insert one element in a singly linked list before a given element. Your program will print the original list, request the user to put in an element to be inserted, and an element to indicate the location of the insertion, then print the final list after the insertion is done. If the element doesn't exist in the list, add the new element to the end of the list. No duplicate values are allowed to store in list. Once you done insertion operation (at least 10 element inserted) in your list, Draw a binary search tree and AVL tree ( show all rotations ) as per your inserted values . Use the following as your test cases to evaluate whether your program works correctly: If you have a linked list: 6à2à7. With user input 8 and 2. Your list should become 6à8à2à7: With user input 8 and -1. Your list should become 6à2à7à8: Let suppose your final linked list . 6à2à7à8à5à10à1à9à3
Can you help me write the code for this one please? Thank you
Use stacks to implement a postfix-to-infix translator. Until the user closes the programme, it should continually read a postfix expression and output the identical infix expression. If the postfix expression entered is incorrect, throw an exception.
Create your own called class called Stack Your class should store items transparently. You should add items using a Push method and remove them through the Pop method. Add an IsEmpty method should return whether there are any items in the stack or not. A CountItems method should tell you the current number of items in the stack Write some code to test your Stack class using the shapes in part 1.