Write a program in PYTHON that uses the Stack implementation given to you in sta

Question

Write a program in PYTHON that uses the Stack implementation given to you in stack.py to reverse a String. The program should ask the user for a String, and should then display the reversed String. The Stack class must be used to reverse the String, one character at a time.

#file-stack.py

# A Stack implementation

class Stack:

    def __init__(self):

        self.__items = []

    def push(self, item):

        self.__items.append(item)

    def pop(self):

        return self.__items.pop()

    def peek(self):

        return self.__items[len(self.__items)-1]

    def is_empty(self):

        return len(self.__items) == 0

    def size(self):

        return len(self.__items)

Explanation / Answer

# This function is used to create an empty stack. It initializes size of stack as 0

def createStack():

    stack=[]

    return stack

# This function is used to determine the size of the stack.

def size(stack):

    return len(stack)

# This function checks if the stack is empty.The stack is empty if the size is 0

def isEmpty(stack):

    if size(stack) == 0:

        return true

# This function is used to add an item to stack . It increases size by 1   

def push(stack,itemone):

    stack.append(itemone)

# This function is used to remove an item from stack. It decreases size by 1

def pop(stack):

    if isEmpty(stack): return

    return stack.pop()

# we will create a stack based function to reverse a string

def reverse(stringone):

    p = len(stringone)

    # This will create an empty stack

    stack = createStack()

    # Now we will push all characters of string to stack one by one.

    for i in range(0,p,1):

        push(stack,stringone[i])

    # now we will make the string empty since all characters are saved in stack   

    stringone=""

    # Finally we will pop all characters of string and put them back to string .This will b in reverse order an it pops from the top.

    for i in range(0,p,1):

        stringone+=pop(stack)

    return stringone

# The driver program to test above functions

stringone="HelloPeople"

stringone = reverse(stringone)

print(" The reversed string is " + stringone)

Related Questions

Navigate

• Browse (All)
• Browse W
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.