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Python program to reverse a string using stack and reversed method
Here, we are going to learn how to reverse a string by using stack and reversed method in python?
Submitted by Sanjeev, on April 11, 2019
Given a string and we have to reverse it by using stack and by using reversed method in python.
1) Reverse a string by using stack
Procedure:
- First create an empty stack
- Push each character one by one in stack
- Pop each character one by one and put them back to the string
2) Reverse a strung using reversed() method
In this method, we will use reversed() method and iterate over the reversed iterator to get the reversed string.
Python code to reverse a string
import sys
def push(element, size, stack):
'''
this function is used to push the elements
in the stack and it will return Error! message
if the stack is full and terminate the program.
'''
global top
if top >= size - 1:
print('Stack Overflow')
sys.exit()
else:
top += 1
stack[top] = element
def pop():
'''
this function is used to pop elements from
the stack and it will return Error! message
if the stack is empty and terminate the program.
'''
global top
if top < 0:
print('Stack Underflow')
sys.exit()
else:
element = stack[top]
print('%s' % element, end='')
top -= 1
def reverse_by_sort(string):
'''
This function is used to reverse any string
by reversed() method.
'''
string = list(string)
rev_str = ''
for i in reversed(string):
rev_str += i
return rev_str
if __name__=='__main__':
size = 11
stack = [0]*size
string = 'Includehelp'
top = -1
# Pushing value in the stack
push('I', 11, stack)
push('n', 11, stack)
push('c', 11, stack)
push('l', 11, stack)
push('u', 11, stack)
push('d', 11, stack)
push('e', 11, stack)
push('h', 11, stack)
push('e', 11, stack)
push('l', 11, stack)
push('p', 11, stack)
print('Original String = %s' % string)
print('\nUsing Stack')
# Popping values from stack and printing them
print('Reversed String = ',end='')
for i in stack:
pop()
print('\n\nUsing sort()')
print('Reversed string = %s' % reverse_by_sort(string))
Output
Original String = Includehelp
Using Stack
Reversed String = plehedulcnI
Using sort()
Reversed string = plehedulcnI
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